Step 1 Heat the oven to 350 degrees. Lightly butter a 9-inch tart pan with a removable bottom.
Step 2 Finely grind the almonds in a food processor. Place the almonds on a baking sheet and toast in the oven until lightly browned, 10 minutes. Remove and cool. Return the nuts to the food processor and add the flour, salt and sugar. Pulse to combine. Cut the butter into small pieces and add to the flour mixture, processing until the ingredients resemble a coarse meal. Add the milk and almond extract and pulse until the dough comes together.
Step 3Turn the dough into the pan and press evenly over the bottom and sides of the pan with floured fingers or a piece of plastic wrap. Leave the oven at the same temperature and bake until the entire crust is lightly browned, 35 to 40 minutes. (This will be all the cooking the crust gets, so err on the side of done-ness.) If the crust puffs up during baking, gently press it down with the back of a fork. Cool slightly. (The crust can be made a day head and held at room temperature, or tightly wrapped and frozen for two weeks.)