In a large bowl, cream the butter and sugar together until light and fluffy, about 3 minutes. You can use a stand mixer, an electric hand mixer, or a fork and some elbow grease to do this. It's up to you.
Add the egg and vanilla and stir until very smooth.
Add the sour cream and stir until combined.
Add the flour, baking powder, baking soda, and salt and stir until well-combined. The dough will be sticky.
Place the dough on a piece of plastic wrap, shape into a disk, wrap well, and refrigerate for at least 4 hours and up to 36 hours.
When you are ready to bake the dough, remove it from the fridge, unwrap, and divide it into 2 pieces. Roll the dough out to 1/2 inch thick on a well-floured surface and cut into shapes (I used a 3-inch circle cookie cutter). Place the cut out cookies on a parchment- or baking-mat-lined cookie sheet and bake at 350 degrees for 10-11 minutes. The tops of the cookies will be light, but the bottom should be lightly brown.
Repeat with remaining dough.
To make the frosting, add the butter, cream cheese, vanilla, 1 tablespoon of cream, and the dash of salt to a large bowl and beat until fluffy, about a minute (a stand or hand mixer works well for this). Add the powdered sugar and beat until smooth and fluffy. If the frosting is too thick, add the additional tablespoon of cream or milk and beat again.
When the cookies are completely cooled, add a generous helping of frosting and top with seasonal fruit that has been cut into bite-sized pieces.
Notes
The chilling step is crucial for easier handling of the dough and to prevent spreading while baking. For best results, ensure the dough is thoroughly chilled.
Use a variety of colors and textures for visual appeal and flavor balance. Consider fruits like strawberries, kiwis, blueberries, and raspberries for a vibrant topping.
If the frosting is too thick, add cream or milk one tablespoon at a time until you reach the desired consistency. If too thin, gradually mix in more powdered sugar.
Keep an eye on the thickness when rolling out your dough. A consistent 1/2 inch thickness ensures even baking and the perfect base for your toppings.
Allow the cookies to cool completely before frosting. Applying frosting to warm cookies can cause it to melt and make the decoration messy.
Assembled fruit pizza cookies are best enjoyed the day they are made. However, you can store the unfrosted cookies in an airtight container for a few days and prepare the frosting and fruit topping just before serving.