# What You'll Need:
→ Vanilla sheet
01 - All-purpose flour — 2 1/2 cups
02 - Baking powder — 2 1/2 teaspoons
03 - Salt — 1/2 teaspoon
04 - Unsalted butter, room temperature — 1 cup (2 sticks)
05 - Granulated sugar — 2 cups
06 - Large eggs, room temperature — 4 eggs
07 - Pure vanilla extract — 1 tablespoon
08 - Whole milk, room temperature — 1 cup
→ Sage green buttercream
09 - Unsalted butter, room temperature — 1 1/2 cups (3 sticks)
10 - Confectioners' (powdered) sugar, sifted — 5 cups
11 - Heavy cream or whole milk — 2 to 3 tablespoons
12 - Pure vanilla extract — 2 teaspoons
13 - Salt — pinch
14 - Sage green gel food coloring — as needed
→ Gold accents
15 - Reserved buttercream — 1/2 cup
16 - Edible gold luster dust — as needed
17 - Clear vanilla extract or vodka (to thin dust) — 1 teaspoon, optional
# Step-by-Step Guide:
01 - Preheat oven to 350°F. Grease a 12×18-inch sheet pan and line it with parchment, leaving an overhang to lift the finished cake.
02 - Whisk together the flour, baking powder, and salt in a medium bowl until evenly distributed.
03 - In a large bowl, beat the room-temperature butter and granulated sugar with an electric mixer on medium-high until light, pale, and fluffy, about 3 to 4 minutes.
04 - Add the eggs one at a time, mixing after each addition until combined, then beat in the vanilla extract.
05 - Alternate adding the flour mixture and the milk in three additions, beginning and ending with the flour, mixing on low speed until just combined and no dry streaks remain.
06 - Transfer the batter to the prepared pan, smooth the top, and 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 - Beat the butter in a large bowl until creamy, then gradually add the sifted confectioners' sugar until fully incorporated; add vanilla, a pinch of salt, and 1 tablespoon of cream at a time until the buttercream reaches a spreadable consistency.
08 - Tint the majority of the buttercream with sage green gel coloring to the desired hue and reserve 1/2 cup of plain buttercream for the gold accents.
09 - Using an offset spatula, spread the sage green buttercream evenly over the cooled sheet, smoothing the surface and cleaning the edges for neat squares.
10 - Combine edible gold luster dust with a few drops of clear vanilla extract or vodka to form a paint; alternatively, stir luster dust into the reserved buttercream for a marbled gold finish.
11 - Pipe details with the reserved buttercream and paint over them with the gold mixture using a food-safe brush, then add sprinkles or celebratory decorations as desired; chill briefly for cleaner slices.
