Preheat oven to 350 degrees F. Grease two 8″ cake pans with butter and lightly flour, or line with parchment paper.

In large bowl, whisk together flour and baking powder. Set aside.

Using an electric mixer on high-speed, whisk together butter and sugar until fluffy and soft, about 3 to 4 minutes.

Add eggs, vanilla, yogurt and milk; mix on medium speed until smooth. Add dry ingredients; mix until well combined being careful to not overmix. Gently fold in 3 cups cranberries.

Pour batter evenly into cake pans; spread evenly.

Bake 35 to 40 minutes or until a toothpick inserted comes out mostly clean and centers are solid. Remove from oven; let cool about 20 to 25 minutes. Remove from pans to cool completely.

In medium bowl, stir together 2 cups cranberries and sugar, tossing until well coated. Set aside.

Place white chocolate chips in heat-safe mixing bowl.

In small pot over medium-high heat, heat heavy cream until it begins to boil. Remove from heat; carefully pour over white chocolate chips. Whisk vigorously until smooth. Set aside.

In bowl of electric mixer, beat 3/4 cups butter until smooth. Add melted white chocolate; beat until combined. Slowly add powdered sugar and vanilla; beat until smooth. If frosting is too thick, add additional heavy cream 1 tablespoon at a time, as needed.

Using large knife or cake slicer, slice a thin layer of cake off tops of each cake to create flat surfaces.

On cake stand, place first cake layer. Evenly cover top with buttercream. Top with second layer of cake; evenly cover top with buttercream. Spread remaining buttercream, evenly and thinly, over top and sides of cake.

Once fully frosted, top with sugared cranberries, if desired. Chill 5 minutes to ensure buttercream sets.