• Preheat the oven to 350°F.
• Line an 8x8 baking dish with parchment paper. ***See Notes
• Using a hand blender or electric mixer, blend butter and cream cheese until fluffy. Add in sugar and mix until well blended. Next, add in vanilla and egg and mix again until blended well.
• Add half of the flour and all of the salt and mix. Continue to mix, gradually adding the remainder of the flour.
• Spread mixture into the parchment lined baking dish and smooth out the top as best as possible.
• Bake in pre-heated oven 25-30 minutes. Test for doneness by sticking a butter knife into the center. Only a little crumb should cling to the knife.
• Cool on a wire rack for 30 minutes.
• Remove cookie bars from pan by lifting the parchment paper by the edges.
• Once bars are completely cooled, frost and add sprinkles. Cut into squares.
• Store leftover bars in refrigerator in an airtight container for up to 5 days.

Frosting

• Beat together butter, vanilla, powdered sugar and 1 tablespoon of the heavy cream until frosting is formed. Add additional tablespoon of heavy cream, if needed to thin consistency.