Preheat oven to 325°F (170°C).

In the bowl of a stand mixer fitted with the paddle attachment, beat butter and sugars at medium-low speed just until combined. Increase mixer speed to medium, and beat until fluffy, 4 to 5 minutes, stopping to scrape sides of bowl. Add eggs and egg yolks, one at a time, beating well after each addition.

In a medium bowl, whisk together flour, salt, and baking powder. In a small bowl, whisk together ¼ cup (60 grams) room temperature water and sour cream. With mixer on low speed, gradually add flour mixture to butter mixture alternately with sour cream mixture, beginning and ending with flour mixture, beating just until combined after each addition. Place half of batter (1⅓ to 1⅔ cups or about 384 grams) in another medium bowl; fold in cocoa, food coloring, and peppermint extract until well combined. Fold vanilla bean paste and remaining ½ teaspoon (2.5 grams) room temperature water into remaining batter until well combined.

Spray a 5-cup Bundtlette pan with baking spray with flour. Divide one-third of red batter among prepared wells, dolloping and spreading in an even layer (about 1 tablespoon or 18 grams per well); top with one-third of vanilla batter, dolloping and spreading in an even layer (about 1 tablespoon or 18 grams per well). (It’s OK if it’s not perfect; if batters start to smudge together, wipe your utensil clean and continue spreading.) Repeat procedure twice until all batter is used. Vigorously tap pan on a kitchen towel-lined counter several times to settle batter and release any air bubbles.

Bake until a wooden pick inserted near center comes out clean, 18 to 24 minutes. Let cool in pan for 15 minutes. Invert cakes onto a wire rack, and let cake cool completely. Using a small fine-mesh sieve, dust with candies, if desired.