Make the crust: Whisk together flour and salt. Cut in cold butter using a pastry blender or your fingers until mixture resembles coarse crumbs. Gradually add ice water, mixing until dough comes together. Do not overmix. Form into a disc, wrap, and refrigerate for at least 30 minutes.

Make the filling: Combine sliced apples, granulated sugar, brown sugar, flour, cinnamon, nutmeg, allspice, and lemon juice. Toss gently to coat.

Preheat oven to 375°F (190°C).

Roll out dough to ⅛ inch thickness. Use a 4-inch cookie cutter or knife to cut out circles. Press each circle into a mini muffin tin.

Fill the pies: Spoon apple filling evenly into prepared crusts. Dot each pie with a small piece of butter.

Bake for 20-25 minutes, or until crust is golden brown and filling is bubbly.

Cool: Let cool in muffin tin for a few minutes before transferring to a wire rack to cool completely. Serve warm or at room temperature.