Make Strawberry Champagne Cake now: a bright, celebratory sheet cake with strawberry-orange cream cheese frosting.
Preheat the oven to 350°F and grease a 9x13-inch rectangular pan. In a large mixing bowl combine the white cake mix, eggs, champagne, vegetable oil, freshly squeezed orange juice, pure vanilla extract, and the bright orange zest; beat the mixture until the batter is smooth and homogenous, pale yellow with tiny flecks of zest. Pour the silky batter into the prepared rectangular pan so the surface is level and even, then bake at 350°F for 18–22 minutes until a toothpick comes out clean. Remove from the oven and allow the cake to cool in the pan until it reaches near-room temperature.
In a saucepan melt the butter, stir in water and granulated sugar and bring to a bubbly boil for about five minutes until the sugar mixture thickens and becomes glossy. Remove from heat and whisk in the champagne until the glaze relaxes into a thinner, translucent liquid; set aside to cool for at least ten minutes, stirring occasionally so it remains smooth. Using a round wooden spoon or similar tool, poke a grid of holes across the top of the cooled cake, then pour the slightly cooled champagne glaze evenly over the entire surface so it seeps into the holes and gives the cake a shiny, saturated top; allow the glazed cake to cool completely on the countertop.

Bring the cream cheese and unsalted butter to room temperature so they blend effortlessly. Beat them together until ultra-smooth and pale, scraping the bowl occasionally, then slowly incorporate the powdered sugar one cup at a time until the frosting thickens. Add the heavy cream (or milk) to loosen and achieve a spreadable but still creamy texture. Fold in the thinly sliced strawberries, a pinch of salt and a final lift of fresh orange zest, then increase the mixer speed briefly so the frosting is uniformly streaked with soft pink strawberry flecks and bright citrus threads.
Spread the cream cheese–strawberry frosting over the fully cooled, glazed cake in an even, slightly swirled layer — the frosting will be relatively thin at first but will set firmer after chilling. Refrigerate the frosted rectangular cake for at least 1–2 hours to firm the frosting and meld the flavors. When ready to serve, slice clean rectangular pieces from the 9x13 pan and plate on delicate white plates with a thin gold rim, garnish with a thin strawberry slice and a curl of orange zest for brightness.
