• Preheat the oven to 350°F and line a baking sheet with parchment paper. Set aside.

To Make The Funfetti Cookie Crumble:

• In the bowl of a mixer, add white sugar, brown sugar, cake flour, baking powder, salt, and sprinkles. Gently mix on low speed until just combined.
• To the bowl, add oil and vanilla and mix on medium speed for about 2 minutes or until clumps form. Transfer the mixture to another bowl and set aside.

To Make The Funfetti Cookies:

• To the empty bowl of the mixer (no need to wash it out), add room-temperature butter and sugar. Beat on medium speed until light and fluffy, about 3-4 minutes. Add eggs and vanilla, and mix, scraping the bowl.
• To the bowl, add cake flour, all-purpose flour, cornstarch, baking powder, and salt. Mix until just combined. Add the sprinkles and gently mix until incorporated. Do not overmix.
• Using a cookie scoop, place dough balls onto the prepared baking sheet, leaving 3-4 inches between each scoop. Gently flatten out each scoop with the side of a glass and then press a generous amount of crumbles into the top of each cookie. 
• Transfer baking sheet to the oven and bake for 10-12 minutes or until the center of each cookie has risen a bit but is still soft, and the sides are firm to the touch.
• Remove baking sheet from oven and let the cookies cool on the baking sheet for about 5 minutes before transferring them to a wire rack to cool completely to room temperature, about 30 minutes.