Step 1

Position a rack in the center of the oven and preheat to 350ºF.

Step 2

In the bowl of a food processor (or a stand mixer fitted with the paddle attachment) combine the almond, sweet rice, and oat flours with the tapioca starch, sugar and salt.

Step 3

Scatter the butter pieces over the top and drizzle with the vanilla extract. Run the mixer until the dough forms moist clumps and the butter is fully incorporated, 20-30 seconds, pulsing as you near the end so as not to over-process the dough. If using a stand mixer, run on medium-low until the dough comes together, 3–5 minutes.

Step 4

If the dough refuses to come together or seems dry after thorough mixing, add up to 1 tablespoon more cold butter or plant butter. Or try adding a few drops of cold water or a little beaten egg or egg yolk. (I've never had this happen, but a few readers have!)

Step 5

Spray a 9-inch loose bottom tart pan (or six 4-inch tartlet pans) with 1-inch high sides lightly with cooking oil. Dump about half of the crumbs into the pan and press the dough evenly into the sides of the pan. Add the remaining crumbs and press them into the bottom, keeping the edges square. (It takes me about 10 minutes to make it look pretty.)

Step 6

Place the tart pan on a rimmed baking sheet and bake until pale golden and firm to the touch (15–20 minutes) for a parbaked crust, or until golden all over (5–10 minutes longer) for a fully baked crust. (If making tartlets, decrease the overall baking time by 5–10 minutes.)

Step 7

Remove the crust from the oven and, while it’s still hot, press the sides and bottom firmly with the back of a spoon or a cup; this will help it hold together when cool.

Step 8

Proceed with your tart recipe.