Preheat oven to 375 degrees.
Lightly flour work surface with 2 Tbsp. of the flour. Roll out one of the pie crust rounds. Using a pizza cutter, cut into four equal quarters. Gently form each pie crust quarter into a 4” tart pan. Press into the bottoms and sides, trimming off any excess crust from the edges of the pan.
In a mixing bowl, top the sliced apples with 2 Tbsp. of flour along with the sugar (or sweetener), cinnamon and nutmeg. Stir together well to coat the apples.
Divide the apple mixture into each prepared tart pan.
Using the second pie crust, using the pizza cutter, cut into 1/2” strips. Top each tart with the strips of crust, alternating the strips in each direction, forming the crust strips to the edges of the tart pan to secure.
Brush the tops of each tart with milk. Lightly sprinkle with sugar or sweetener.
Place the tarts on a baking sheet and lightly tent the tarts with aluminum foil to prevent the crust from over-browning. Bake for 30 minutes. Remove the foil and continue to bake the tarts for 15-20 more minutes or until golden brown.
Remove from oven and let cool to room temperature before serving.