Step 1: In a large bowl, whisk together the flour and salt. Cut in the cold butter using a pastry cutter until the mixture resembles coarse crumbs.
Step 2: Gradually add ice water, one tablespoon at a time, mixing until the dough just starts to come together. Form into a disk, wrap in plastic, and refrigerate for at least 30 minutes.
Step 3: While the dough chills, melt 2 tablespoons of butter in a skillet over medium heat. Add the diced apples, brown sugar, cinnamon, nutmeg, and lemon juice. Cook for 5-7 minutes until apples are slightly tender. Stir in the toasted pecans and set aside to cool.
Step 4: Preheat your oven to 375°F (190°C). Roll out the chilled dough on a lightly floured surface to about 1/8-inch thickness.
Step 5: Use a circular cutter to cut out rounds and press them into a greased muffin tin or tartlet pans. Prick the bottoms with a fork.
Step 6: Fill each pastry shell with the spiced apple pecan mixture. Bake for 20-25 minutes, or until the pastry is golden brown. Cool slightly before removing from the tin.