Preheat your oven to 350°F and line baking sheets with parchment paper. Cream the butter and sugar until light and fluffy, then add the egg, yolk, and vanilla. Mixing thoroughly ensures soft and flavorful cookies.
In a separate bowl, whisk together flour, baking soda, cream of tartar, and salt. This ensures even distribution of leavening agents so your cookies bake uniformly.
Add the dry ingredients to the wet mix and stir just until combined. Use a cookie scoop to portion dough and chill for 10 minutes; this prevents spreading during baking.
Bake cookies at 350°F for 10–12 minutes until edges are lightly golden. Let them cool completely before frosting to avoid melting the cream cheese layer.
Whip cream cheese, butter, powdered sugar, vanilla, and lemon zest until smooth. Spread frosting generously and top with fresh fruit, arranging colors for a beautiful presentation.