• Preheat oven to 350ºF. Line a 9×13 cake pan or baking dish with foil or parchment paper. If using foil spray with cooking spray (preferable with flour in it!)
• In the bowl of a stand mixer, or a large bowl if using a hand mixer, beat together the butter and cream cheese until smooth. Add in the sugar, and mix well, scraping down the sides of the bowl, as necessary.
• Add the egg and vanilla and mix.
• Add the flour, baking powder, and baking soda and mix on low speed until a soft dough forms.
• Spread the dough evenly into your prepared pan (use your hands, the bottom of a glass, etc. if necessary to make it easier!) Bake for 20 minutes. Remove from oven and cool completely, before frosting.

For the Raspberry Buttercream

• In a small saucepan combine raspberries and lemon juice; bring to a simmer over medium heat and cook, stirring constantly and gently smashing the raspberries, until thickened and reduced, about 10 minutes. Remove from heat.
• Using a fine-mesh strainer over a small bowl, pour in the raspberry puree and push through the strainer with a spatual, which will give you smooth puree with no seeds. Set aside to cool.
• In the bowl of a stand mixer fitted with the paddle attachment, beat the softened butter on medium-high speed (scraping down the sides as needed) until completely smooth, about 2 minutes. Add in the raspberry puree and beat until completely combined, about 1 minute (the mixture may look very “wet”, but don’t worry!) Add in the powdered sugar, one cup at a time, on low speed, until smooth.
• Spread the frosting evenly over the cooled cookie base and add the sprinkles. Cut into squares (I did 4×6 rows, to make 24 bars!) Serve and enjoy!