Thumbprint cookies are a common American treat that I've seen since I was a kid. They're basically shortbread cookies with an extra zing of sweet jam (or tart if you're so inclined).
Ingredients
1 cup butter (2 sticks) at room temperature
1/2 cup granulated sugar
2 large eggs, room temperature
1 tsp vanilla extract
1/4 tsp salt
2 1/2 cups gluten-free 1:1 baking flour
3/4 cup jam, any kind
1 cup chopped nuts (optional)
Directions
1. Beat butter and sugar on high speed for about three minutes. Add eggs* and vanilla to butter mixture and mix until blended.
*If you are using the nut option, separate eggs into yolks and whites, saving the whites to 'glue' the nuts to the outside of the cookies. Reduce the flour by 1/2 cup.
2. Add flour and salt to the butter mixture and mix until just combined but no powder is left.
3. Chill the dough in the fridge uncovered for about 30 minutes until stiff.
4. Pre-heat oven to 350 F (177 C) and line 2 baking sheets with parchment paper.
5. Roll the dough into ~1" balls (about a Tbsp of dough) and place them on the parchment lined sheets spaced about 2 inches (5 cm) apart.**
** If using nuts, whisk the egg whites until frothy and dip the dough balls into the froth. Then roll them in the chopped nuts until covered.
5. Press down gently on each ball with your thumb to make a small well in the center of the cookie. Fill the well with about 1/2 tsp of jam.
6. Bake the cookies for 12-15 minutes or until slightly firm. Allow to cool for a few minutes on the baking sheets to firm up before moving them to a wire rack to cool completely.