# What You'll Need:
→ Vanilla sheet cake
01 - 2 1/2 cups all-purpose flour
02 - 2 1/2 teaspoons baking powder
03 - 1/2 teaspoon fine salt
04 - 1 cup unsalted butter, room temperature
05 - 2 cups granulated sugar
06 - 4 large eggs, room temperature
07 - 1 tablespoon pure vanilla extract
08 - 1 cup whole milk, room temperature
→ Sage green buttercream
09 - 1 1/2 cups unsalted butter, room temperature
10 - 5 cups powdered sugar, sifted
11 - 2 to 3 tablespoons heavy cream or whole milk
12 - 2 teaspoons vanilla extract
13 - Pinch of fine salt
14 - Sage green gel food coloring, as needed to tint
→ Gold buttercream accents
15 - 1/2 cup reserved buttercream (set aside from main batch)
16 - Gold edible luster dust, as needed
17 - 1 teaspoon clear vanilla extract or vodka (optional, to mix with dust)
# Method:
01 - Preheat oven to 350°F. Grease a 12×18-inch sheet pan and line the bottom with parchment, leaving an overhang for easy removal.
02 - In a medium bowl, whisk together the all-purpose flour, baking powder, and salt until evenly combined.
03 - In a large bowl using an electric mixer, beat the room-temperature butter and granulated sugar on medium-high speed until light and fluffy, about 3 to 4 minutes.
04 - Add the eggs one at a time, beating well after each addition, then mix in the vanilla extract until incorporated.
05 - Add the flour mixture to the butter mixture in three additions, alternating with the milk and beginning and ending with the flour; mix on low speed until just combined—do not overmix.
06 - Transfer the batter to the prepared pan and smooth the surface. Bake 28 to 32 minutes, or until a toothpick inserted in the center comes out clean. Cool completely in the pan on a wire rack.
07 - In a large bowl, beat the butter on medium speed until creamy. Gradually add the sifted powdered sugar, beating well between additions. Add vanilla, salt, and then cream 1 tablespoon at a time until the buttercream reaches a spreadable consistency.
08 - Tint most of the buttercream with sage green gel coloring until you reach the desired hue. Reserve 1/2 cup of uncolored or lightly colored buttercream for gold accents.
09 - Spread the sage green buttercream evenly over the cooled sheet cake using an offset spatula, smoothing to an even finish.
10 - Mix gold edible luster dust with a few drops of clear vanilla or vodka to create a paintable suspension, or blend the dust into the reserved buttercream for a marbled gold effect. Apply using a food-safe brush or piping to add accents.
11 - Pipe any graduation motifs or borders, add gold sprinkles as desired, then chill briefly to set the buttercream before slicing into neat squares.
