1. Infuse Buttermilk for Cake:

• In a bowl, combine the buttermilk and 1/2 cup Fruity Pebbles cereal. Stir and set aside while you prepare other ingredients (allow at least 15-20 minutes for flavor to infuse). Do not strain yet.

2. Prepare Pans and Dry Ingredients:

• Line the bottoms of three 6-inch round cake pans with parchment paper. Grease the sides (or use baking spray with flour). Preheat the oven to 350°F (180°C).
• In a medium bowl, whisk together the all-purpose flour, kosher salt, and baking powder. Set aside.

3. Mix Wet Ingredients for Cake:

• In the bowl of a stand mixer fitted with the paddle attachment, cream together the room temperature butter, canola oil, and granulated sugar on medium speed for about 3 minutes, until light and fluffy.
• In a small bowl, whisk together the room temperature eggs, vanilla extract, and lemon extract.
• With the mixer on medium-low speed, slowly stream the egg mixture into the butter/sugar mixture. Mix until fully combined, scraping down the bowl as needed.

4. Combine Batter:

• Add about one-third of the dry ingredients to the mixer bowl. Mix on low speed until almost combined.
• Strain the Fruity Pebble-infused buttermilk, discarding the solids. Add half of the infused buttermilk to the batter and mix on low until just combined.
• Alternate adding another third of the dry ingredients, the remaining buttermilk, and ending with the last third of the dry ingredients. Mix on low speed after each addition only until just combined. Do not overmix.

5. Bake the Cakes:

• Divide the batter evenly among the three prepared 6-inch cake pans (about 370 grams per pan, if weighing).
• Use an offset spatula to smooth the tops.
• Bake for about 26 minutes, or until the tops bounce back when lightly touched and a skewer inserted into the center comes out clean or with a few moist crumbs.
• Let the cakes cool in the pans on wire cooling racks for 20 minutes.
• Run a thin knife or offset spatula around the sides of the pans and carefully invert the layers onto the racks. Remove parchment paper and let cool completely.

6. Make the Cereal Milk:

• In a small bowl, combine the 1/4 cup Fruity Pebbles and 4 tablespoons of milk. Stir and set aside. You will use the milk (not the solids) later.

7. Make the Cereal Cake Crumb:

• Preheat oven to 300°F (150°C). Line a baking tray with parchment paper.
• In a bowl, combine the melted butter, flour, sugar, 1/2 cup Fruity Pebbles, vanilla extract, and baking powder. Stir with a spoon until it forms crumbly pieces.
• Spread the crumbs out onto the lined baking tray.
• Bake for 15 minutes. Set aside to cool completely.

8. Make the Cereal Milk Buttercream:

• In the bowl of a stand mixer fitted with the paddle attachment, beat the room temperature butter on medium speed until smooth and lump-free.   
• Reduce speed to low and gradually add the powdered sugar. Mix until combined.
• Increase speed to high and beat for 2-3 minutes until the buttercream is light and fluffy.
• Strain the cereal milk you made earlier, discarding the solids. Add 2 tablespoons of the infused milk to the buttercream. Mix on low until combined.

9. Assemble the Cake:

• Once cake layers are completely cool, use a long serrated knife to level the tops, removing any domes to create flat surfaces.
• Place the first cake layer (cut side up) on your serving plate or cake stand. Use a pastry brush to lightly brush the layer with some of the strained cereal milk.
• Spread an even layer of the cereal milk buttercream over the cake layer.
• Sprinkle about 1/4 cup of the cooled cereal cake crumb evenly over the frosting.
• Place the second cake layer on top. Brush with cereal milk, spread with buttercream, and sprinkle with another 1/4 cup of cake crumb.
• Place the third cake layer on top, upside down (bottom side facing up) for a super flat top surface. Brush this layer with cereal milk as well.

10. Frost the Cake:

• Apply a thin “crumb coat” of the remaining buttercream over the entire cake (top and sides) to trap any loose crumbs. Chill for 15-20 minutes.
• Apply the rest of the buttercream smoothly over the top and sides of the cake. (The recipe notes suggest making a double batch if you like a thicker layer of frosting).

11. Decorate:

• Gently press the remaining cereal cake crumbs onto the top edge or sides of the cake, or sprinkle them over the top surface.
• Enjoy immediately or refrigerate until ready to serve.