Prepare Homemade Cherry Filling (if using): In a saucepan over medium heat, combine pitted cherries, sugar, and lemon juice. Stir frequently and bring to a boil for about 5 minutes. Mix cornstarch with water to create a slurry, add to the pan, and cook until thickened (about 2-3 minutes). Chill in the refrigerator.

Preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper.

Mix Dry Ingredients: In a mixing bowl, whisk together almond flour, tapioca flour, and salt until smooth.

Cream Butter and Sugar: Use an electric mixer to cream the butter and sugar until light and fluffy (about 3-5 minutes). Stir in vanilla and almond extracts.

Combine and Form Dough: Gradually add the dry mixture into the butter-sugar blend until a pliable dough forms. Roll into balls, about one inch in diameter, then coat with granulated sugar.

Create Thumbprints: Using a measuring spoon, press into the center of each dough ball to create an indent. Fill with the chilled cherry pie filling.

Bake: Place the baking sheet in the oven and bake for 14-15 minutes until lightly golden. Cool for 5 minutes on the sheet before transferring to a wire rack.