These creepy (and easy!) Halloween cakes are perfect for any party! Spongy mini buttermilk bundts are drenched with red glaze and speared with candy knives.
In a medium bowl, whisk together flour, baking powder, and salt, then set aside.
Using a stand mixer (or hand mixer + large bowl), beat together butter and sugar on medium-high until fluffy and crumbly, about 2-3 minutes.
Drop mixer speed to low and add in eggs and vanilla, then mix until incorporated, about 1 minute.
Keeping speed on low, add about 1/3 of the dry ingredients to the batter. Next, follow with 1/2 of the buttermilk. Continue alternating between the dry ingredients and the buttermilk until all have been added and batter looks smooth with dry ingredients fully incorporated.
Pour batter into prepared mini bundt cake pans, filling each cavity about 3/4 to 4/5 full. This recipe typically makes enough for 9 complete mini bundts with a little a bit of batter left over. Go ahead and add the remaining batter to a 10th pan (can be any size the batter fits in) and bake it. The 10th cake will be crumbled and used to create the "brain matter" that helps keep the candy knives in place.
Place filled mini bundts pans on a baking sheet and bake for 20-30 minutes or until a toothpick tester comes out clean.
Let mini bundts cool (still in their pans) for 20 minutes, then remove mini bundt cakes from their pans and transfer to a wire cooling rack to cool completely.
For the Red Glaze
In a large bowl, whisk together powdered sugar, milk, vanilla, and red food coloring. If desired, add more red food coloring for a deeper color.
Check the consistency of the glaze; you may get different results depending on the type of food coloring used. You want the glaze to be thick enough that it's not too drippy but liquid enough that it will fall down the cake. If you'd like, test how the glaze falls on the 10th bundt cake you prepared (the one that will be used for crumbling). If you need a thinner glaze, add more milk, 1/2 teaspoon at a time. If you need the glaze thicker, add more powdered sugar, 1/4 cup at a time.
Putting it all together
Place your 10th bundt cake in a small bowl and crumble it into small pieces. Add about 1 tablespoon of the red glaze to the bowl and then thoroughly mix it with the cake crumbles. I like to call this the "brain matter."
Scoop up 1-2 tablespoon of the brain matter and roll it into a tight ball. Place the brain matter ball on the top indentation of the bundt cakes. Repeat this step for all the bundt cakes you have.
Using a pastry bag (or a Ziploc bag with a hole in the corner), drizzle the red glaze on top of the brain matter in the center of the mini bundts, then drizzle it down the grooves of the bundt.
Finish by placing a candy knife in the center of the bundt, securing it in the brain matter under the frosting.