The butter tart is celebrated in its homeland, where preferences for it are a matter of passionate national debate.

Sara Bonisteel

You could be forgiven if you’ve never eaten a butter tart. There is no flashy frosting or elaborate lattice to entice you. It’s easy to pass by.

But Canadians will tell you that these diminutive treats hold an expanse of flavor and textures: flaky pastry, caramelized crust and a bracingly sweet filling.

The butter tart is celebrated in its homeland, where the preference for runny or firm fillings, plain or with raisins, is a matter of passionate national debate. Ontario, where most scholars believe the butter tart was born, celebrates it with two dueling tourism trails (Kawarthas Northumberland Butter Tart Tour and Butter Tarts and Buggies) and festivals galore, including Ontario’s Best Butter Tart Festival in Midland and a new one that will have its debut in March in Bowmanville, east of Toronto.

“Good butter tarts, they seem like a modest dessert,” said Michael DeForge, a creator of TartQuest, an Instagram feed of butter tart reviews. “They’re supposed to pack a lot of punch. But on the outside, they’re supposed to just seem plain and unassuming.”

Modern Canadian culinary culture celebrates seasonality, native ingredients and provincial pride. Like poutine and Nanaimo bars, two other national favorites, butter tarts buck the norm. They are a humble treat, made with ordinary ingredients, and spectacularly delicious.

“If you look at the ingredients, it’s really what you have in your pantry when you have nothing else,” said Liz Driver, author of “Culinary Landmarks: A Bibliography of Canadian Cookbooks, 1825-1949.”

At its most basic, the butter tart is a pastry filled with brown sugar, butter and egg. Oven alchemy transforms those simple ingredients. Inventive cooks have gone further with chocolate chips, coconut, nuts and other add-ins.

Unlike the Nanaimo bar — a midcentury British Columbian creation made with processed ingredients like custard powder and graham crackers — the butter tart goes back at least to the 19th century.

Mary F. Williamson, a retired fine arts librarian at York University in Toronto, traced the earliest mention to 1900 and the “Royal Victoria Cook Book,” published to raise money for the Royal Victoria Hospital in Barrie, Ontario. Margaret MacLeod’s recipe for “Filling for Tarts” (like some of the other community cookbook contributors, she was identified by her husband’s name, Mrs. Malcolm MacLeod) called for one cup of sugar, a half-cup butter, two eggs and a cup of currants.

There are as many theories about the origins of the tart as there are variations. The brown sugar pie, the Scottish border tart, Bakewell tarts and the Quebec sugar pie — each has been named a predecessor to the Canadian tart.

“Each of those things is their very own particular thing, very similar to each other, but they’re not all the same,” Driver said.

The very first butter tart recipe may never be found, because until recently cookbooks were not seen as items worth preserving.

“Most of these things were developed by housewives, and it wasn’t deemed important,” said Lenore Newman, the author of “Speaking in Cod Tongues: A Canadian Culinary Journey.” “Now that we’re actually interested in it, we go back, and we find there are a lot of holes in this knowledge. I think we can safely say they’re Canadian and that they’re definitely still popular.”

By the 1910s, the butter tart was all the rage in the farming regions of Ontario. Three recipes for tart filling and six recipes for butter tarts appear in “Canadian Farm Cook Book” of 1911. “Junia,” a columnist for The Farmer’s Advocate, shared reader recipes in early 1913 to answer a question from N.W. of Ontario who longed for a butter tart recipe — “the crust and all, as I am a new beginner.” Readers responded with tart recipes plain and with currants, proof perhaps that the filling debate over plain or dried fruit is more than a century old.

Butter tart recipes, and variations like butter tart ice cream, regularly appear in magazines like Canadian Living.

Elizabeth Baird, who was food editor of the magazine from 1987 to 2009, was a student at the University of Toronto when she realized the power of their appeal.

“I worked in a summer lodge where there were a lot of American visitors, and we could wow them every time with butter tarts with vanilla ice cream,” Baird said. “I think that was the first time I realized they were unique to Canada.”

Why, then, have the tarts never made significant waves south of the border? It could be that Canadians don’t want to let the world — or just their louder neighbors — in on their sweetest secret.

“You have so many things of your own,” Driver said with a laugh. “You don’t need a Canadian butter tart.”

Yield: 1 dozen

Time: 45 minutes, plus chilling and cooling

1 1/2 cups (191 grams) all-purpose flour, more for dusting

Pinch of fine sea salt

1/2 cup (113 grams) cold unsalted butter or lard

(103 grams), cubed

1/4 cup (60 milliliters) ice water 1 large egg yolk

1 teaspoon white vinegar

1/4 cup (36 grams) raisins

(optional)

1 cup (220 grams) packed

brown sugar, light or dark 1/2 teaspoon fine sea salt

1/4 cup (57 grams) unsalted

butter, softened 1 teaspoon vanilla extract

1 large egg

1: Make the pastry: In a large mixing bowl, combine flour and salt. Using a pastry blender or your fingertips, rub butter or lard into flour until mixture is in peasize pieces.

2: In a small bowl, mix water, egg yolk and vinegar until well combined. Add liquid to the flour mixture, using a fork to combine. Add 1 tablespoon more water if it looks dry.

3: Knead dough several times by hand to bring it together and shape into a flat square. Wrap with plastic and refrigerate for at least 30 minutes.

4: Once chilled, roll out the dough into a 16-inch-by-12inch (40.5 centimeters by 30.5 centimeters) rectangle about

1/8- to 1/4-inch (3 to 6 millimeters) thick. Flour the work surface and rolling pin as you work with the dough.

5: Use a circular 4-inch (10 centimeter) cookie cutter (or a clean 28-ounce [496 milliliter] can) to cut 12 pieces. Reroll dough if needed to cut more circles, but try to cut as many pieces on the first pass. With your fingertips, press each circleinto the cup of a standard muffin tin, so that the edge of the dough is flush with the pan. Refrigerate while you make the filling.

6: In a bowl, cover raisins with hot tap water to plump. Heat oven to 425 degrees F (220 degrees C).

7: Make the filling: In a bowl, mix brown sugar and salt, and then beat the butter into the sugar by hand until smooth. Add vanilla and egg and mix until combined. Do not use an electric mixer; it will add too much air to the filling.

8: Drain the raisins and place seven or eight raisins in each chilled tart shell.

9: Divide the filling evenly among the tart shells, filling each one about halfway. Place muffin tin on a baking sheet. Bake 13 to 15 minutes for a runnier tart and 17 to 19 minutes for a firmer one.

10: A few minutes after removing the tarts from the oven, run a knife or offset spatula around the edge of each tart to loosen. Let cool completely in the tin. To remove, run a butter knife or offset spatula around and under each tart to pop it out of the tin.

Yield: 25 squares

Time: 45 minutes, plus chilling

1 cup (159 grams)

all-purpose flour

1/4 cup (55 grams) packed brown

sugar, light or dark

Pinch of fine sea salt

1/2 cup (113 grams)

cold unsalted butter, cubed

1/3 cup (76 grams) unsalted butter, softened tablespoons

1 teaspoon vanilla extract

1/2 cup (72 grams) raisins,

roughly chopped (optional) 1 cup (220 grams) packed

brown sugar, light or dark 1 large egg, beaten 1 tablespoon all-purpose flour

1: Heat oven to 350 degrees F (180 degrees C). Make the crust: In a bowl, combine flour, brown sugar and salt. Usinga pastry blender or your fingers, cut in butter until well combined and crumbly. It will be dry and sandy. Press flour mixture evenly into a 9-inch (23-centimeter) square pan and bake for 15 minutes.

2: As the crust bakes, make the filling: In a bowl, mix butter, cream, vanilla, raisins (if using), brown sugar, egg and flour until combined. Spread to edges over partly baked crust.

3: Return to oven and bake 14 to 20 minutes more or until golden brown (squares made with dark brown sugar will beadeeper shade of amber). A few minutes after removing it from the oven, run a knife or offset spatula around the edges to loosen any sugar that is stuck to the pan. Let pan cool to room temperature, then chill in a refrigerator. Once cold, use a sharp knife to slice into squares, approximately 1 3/4 inch (4.5 centimeters).