In a small bowl, stir together the flour, baking powder, baking soda and salt until well-mixed. Set aside.
In a large bowl, beat together the butter and white sugar for 2 minutes until light and fluffy.
Beat in the eggs and extracts for 1 minute, then beat in the yogurt until just combined.
Add half of the dry ingredients, beat until just combined, then the milk, then remaining half of the dry ingredients.
Stir in the sprinkles to your personal preference, adding more or less as desired.
Pour the batter into the prepared baking dish and use the back of a spoon or an offset spatula to smooth the batter down to be completely even.
Bake for 28-35 minutes, until an inserted toothpick comes out clean.
Allow the cake to cool completely before frosting.
While the cake is cooling, prepare the raspberry buttercream frosting.
In a large bowl, beat together the butter and 4 cups of powdered icing sugar for 2 minutes.
Add the optional cream and vanilla extract and beat until incorporated.
Add the raspberries and beat until the raspberries are broken down and no large pieces remain in the frosting.
Spread the frosting over the cooled cake with an offset spatula and then garnish with sprinkles.
Notes
This Recipe Can be Doubled: If you are looking to make this birthday funfetti cake for larger crowd, double and split between 2 casserole dishes or sheet pans.
Switch up the Frosting: If you are not a fan of fruit flavors in frosting, you can also use vanilla buttercream for the raspberry frosting in this recipe.
Use Parchment Paper: To easily remove cake from casserole dish, line with parchment paper before filling with batter.