Preheat oven to 350°F (175°C). Then, line 2 baking sheets with parchment paper.
In a large mixing bowl, beat the butter and sugar together until light and fluffy, about 2 minutes.
Add the egg yolk, vanilla, and almond extract, and mix until well combined.
In a separate bowl, whisk together the all-purpose flour, almond flour, and salt.
Add the dry ingredients to the wet ingredients and mix on low until a soft dough forms.
Scoop the dough with a 1-tablespoon cookie scoop (about 20 g each). Roll into smooth balls and place on prepared baking sheets, spacing about 2 inches apart.
Use your thumb or the back of a ½-teaspoon measuring spoon to press an indentation into the center of each ball. If cracks form, gently press them back together. Chill the shaped cookies in the fridge for 20–30 minutes (this helps prevent spreading). For a more rustic look: Fill the cookies with jam before baking, knowing it may bubble slightly. Otherwise wait until the cookies have baked to add the jam.
Bake for 12–14 minutes, or until the edges are just turning lightly golden.
Halfway through baking (around 10 minutes), remove the cookies and gently press the wells again if they’ve puffed. Return to the oven to finish baking.
For the neatest look: Allow the cookies to cool for 5 minutes. Warm the jam gently in a small saucepan over low heat (or in the microwave in 10-second bursts) until smooth and glossy. Spoon or pipe about ½–¾ teaspoon of the warm jam into each well. Let the cookies cool completely on a wire rack. The jam will thicken as it sets.