Preheat oven to 375° F. Line 2 baking sheets with parchment paper.
In the bowl of an electric mixer fitted with the paddle attachment, cream the butter and sugar together until light and fluffy, scraping the sides of the bowl as necessary.
Add the egg yolks, lemon extract and food coloring (if using) and beat until fully combined.
Add the flour and salt to the bowl. Turn mixer onto low until just incorporated and then increase the speed and combine completely until a dough is formed. Remove bowl from mixer.
Scoop dough out a few tablespoons at a time and roll into a ball. Place on the prepared baking sheets. With your thumb or the back of a teaspoon, press the center down to create and indent. Continue until all dough is used.
Bake cookies for 8 minutes. Remove from oven. Use a teaspoon to re-press the indents down. Fill with jam and place back into the oven to bake for an additional 4-5 minutes until edges are slightly browned and jam has set.
Remove from oven and allow to cool slightly on the baking sheet. Finish cooling on a wire rack. Dust with confectioners’ sugar prior to serving, if desired.