In a bowl, whisk together 1.75 cups all-purpose flour, 1 teaspoon baking soda, ½ teaspoon baking powder, and ⅛ teaspoon salt; set the dry mixture aside.

In a large mixing bowl, beat ½ cup softened unsalted butter and 1 cup granulated sugar until light and fluffy, about 2 minutes.

Add 1 large egg and 2 teaspoons vanilla extract to the butter-sugar mixture and beat until combined.

Add the dry ingredients to the wet ingredients and mix just until the flour is incorporated. Do not overmix.

Stir ¼ cup funfetti into the cookie dough until evenly distributed.

Cover the dough and chill in the refrigerator for at least 2 hours, or preferably overnight.

When ready to assemble, preheat the oven to 350°F (175°C). Line an 8" square baking pan with parchment paper, leaving an overhang for easy removal.

Prepare the cheesecake filling: In a clean bowl, beat 8 oz softened cream cheese until smooth and creamy.

Add ½ cup powdered sugar and 1 teaspoon vanilla extract to the cream cheese and beat until combined.

Add 1 large slightly beaten egg to the cream cheese mixture and beat on medium speed just until combined. Fold in ¼ cup funfetti sprinkles.

Remove the chilled cookie dough from the refrigerator. Reserve roughly ¼ of the dough for the topping and press the remaining ¾ evenly into the bottom of the prepared 8" pan to form the crust.

Pour the cream cheese filling over the cookie crust and spread it into an even layer.

Crumble the reserved cookie dough with your hands and scatter the crumbles evenly over the top of the filling.

Bake the bars at 350°F for 25–30 minutes, or until the top is golden brown and the filling is set (the center may still have a slight jiggle).

Cool the pan completely on a wire rack; the bars will sink slightly as they cool. Use the parchment overhang to lift the bars from the pan, then cut and serve.

Refrigerate any leftovers for up to 3 days.