Preheat the oven to 350 degrees. Prepare two large baking sheets by lining with parchment paper, greasing or spraying with cooking spray.

Stir together flour, baking soda, baking powder and salt in a medium bowl. Set aside.

In a large bowl, combine the butter, sugar and egg yolk. Beat at medium speed with an electric mixer until fluffy and well blended. Add the cream cheese, vanilla and lemon zest beating until evenly incorporated.

On low speed, beat in the flour mixture until well blended. Let stand for 5 to 10 minutes or until dough firms up slightly.

Shape portions of the dough into approximate 1-inch balls. Dip the tops of the balls into the chopped nuts, if using. Place the balls, nut side up, on the baking sheets, about 1 ½ inches apart. Using your thumb, press a deep well into the center of each ball. Place about ¼ teaspoon jam in each indentation.

Bake the cookies, one sheet at a time, in the upper third of the oven for 9 to 12 minutes or until the cookies are just barely brown at the edges. Reverse the baking sheet halfway through baking to ensure even browning. Transfer the baking sheet to a wire rack and let stand until cookies firm up slightly, about 2 to 3 minutes. Remove the cookies from the pan and place them on the wire rack to cool completely.

Store in an airtight container for up to two weeks or freeze for up to a month.