For the crust
5 1/2 ounces all-purpose flour (approximately 1 1/4 cups)
4 1/2 ounces cake flour (approximately 1 cup)
6 tablespoons light brown sugar
1/2 teaspoon salt
8 ounces (16 tablespoons) good-quality unsalted butter, melted
1 teaspoon vanilla bean paste or vanilla extract
For the filling
4 ounces (8 tablespoons) unsalted butter
1/2 cup packed light brown sugar
1/2 cup pure maple syrup, preferably grade B
2 tablespoons creme fraiche or heavy cream
1 teaspoon vanilla bean paste or vanilla extract
Pinch of salt
12 ounces chopped pecans (about 3 cups)
For the crust, preheat oven to 350°F. Line a 9x13-inch baking dish with aluminum foil or parchment paper, leaving a 2-inch overhang on all sides for easy removal of the bars. A Pyrex baking dish is recommend; baking times may vary slightly if using ceramic or metal.
Combine the all-purpose flour, cake flour, brown sugar, and salt in a medium mixing bowl. Pour in the melted butter and vanilla and, using a fork, stir until it forms a thick, sandy dough. It should be fairly moist and will seem a bit greasy at this point.
Transfer the mixture to the prepared baking dish and press evenly into the bottom. Transfer the dish to the freezer for 10 minutes (or the refrigerator for 30) to allow the dough to firm. Bake for 18 to 20 minutes, until the crust is set and dry on top, but not yet turning golden (a bit of golden color around the edges is ok). Allow the crust to cool for at least 20 to 30 minutes before adding filling.
For the filling, heat the butter, brown sugar, and maple syrup in a medium saucepan over medium heat until the butter is melted and the sugar is dissolved. Turn off heat and whisk in creme fraiche, vanilla, and salt. Fold in the pecans. At this point, the topping will be very loose and liquidy.
Pour the mixture over the baked shortbread crust and use an off-set spatula to spread the pecans evenly. Bake in the 350°F oven for 18 to 20 minutes, until mixture is hot and very bubbly around the edges.
Remove from the oven and allow to cool and set overnight — the topping will still be a bit loose when you first take the bars from the oven, but they will gradually firm up. (If you need to cut the bars sooner, once the pan is cool, place the bars in the fridge for a few hours to help them set more quickly.)
To slice the bars, lift them out of the pan using the parchment paper and cut them into squares on a cutting board. Store bars, covered, at room temperature for up to 5 days.
Recipe Notes
- You can use all all-purpose flour if you don't have any cake flour on hand (Pastry flour would also be great.)
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