Preheat oven to 325°F (170°C). Spray 2 (8-inch) round cake pans with baking spray with flour. Line bottom of pans with parchment paper.

In a medium bowl, whisk together sugar and orange zest until sugar is fragrant, about 1 minute.

Assemble Ankarsrum mixer with stainless steel bowl. Place dough knife in smaller hole, and position dough roller just off the side of bowl. Add butter, and beat by slowly increasing mixer speed to medium-high (6 o’clock) until creamy, about 1 minute, using scraper to help move butter around. (Butter might stick to the roller in the beginning.) Slowly add sugar mixture, scraping bowl frequently. Let mix until well combined and lightened in color, about 3 minutes. Add eggs, beating until just combined. Beat in vanilla.

In a medium bowl, whisk together flour, baking powder, and salt. With mixer on lowest speed (12 o’clock), gradually add flour mixture to butter mixture. Move roller to 1 inch away from side of bowl, and increase mixer speed to medium-low (2 o’clock), mixing until combined.

In another medium bowl, whisk together milk, orange juice, and oil. With mixer running, slowly add milk mixture to batter, beating until combined. Divide batter between prepared pans (about 2½ cups or 665 grams each).

Bake until a wooden pick inserted in center comes out clean, 40 to 45 minutes. Let cool in pans for 10 minutes. Remove from pans, and let cool completely on wire racks.

Level cooled cake layers if desired. Place 1 cake layer on a serving plate. Spread 1½ cups (360 grams) Cranberry Buttercream on cake layer. Top with remaining cake layer. Spread remaining buttercream on top and sides of cake. Refrigerate for at least 30 minutes before serving. Garnish with sugared cranberries, if desired. Cover and refrigerate for up to 3 days.

In a medium saucepan, bring cranberries, orange juice, and granulated sugar to a boil over medium-high heat, stirring occasionally. Cook, stirring frequently, until cranberries have burst and mixture has thickened, 3 to 5 minutes. Remove from heat, and let cool completely. (You should have about ½ cup mixture.)

Transfer cranberry mixture to the work bowl of a food processor, and purée until smooth. (Alternatively, use an immersion blender to purée the mixture.)

Assemble Ankarsrum mixer with beater bowl and cookie beaters. Add butter; beat at medium-low speed (2 o’clock) until smooth. Gradually add confectioners’ sugar, beating until well combined and stopping to scrape sides of bowl. With mixer on low speed (12 o’clock), add salt, vanilla, and cooled cranberry mixture, beating until combined and stopping to scrape bowl thoroughly. Increase mixer speed to medium (4 o’clock), and beat until fluffy, 1 to 2 minutes. Use immediately.