Make No-Bake Mimosa Cheesecake for a silky, chilled dessert. Make No-Bake Mimosa Cheesecake tonight and garnish with fresh orange zest.
Lightly grease a 9-inch springform pan and line the bottom with a circle of parchment. Grind graham crackers to a fine, even crumb in a food processor, then pour the melted butter into a shallow matte grey ceramic bowl with the crumbs and stir until every particle glistens and holds together when pinched. Press the mixture firmly into the bottom and up the sides of the prepared pan with the back of a measuring cup or the base of a glass to form a compact, even golden crust. Transfer the pan to the refrigerator or freezer to chill while you prepare the filling.
Gently melt the white chocolate with five tablespoons of heavy cream in short bursts and stir to a glossy, pourable emulsion; set it aside to cool until just warm. Chill a mixing bowl and whisk, then whip 1 1/4 cups heavy cream with powdered sugar to soft then stiff peaks — glossy, billowy peaks that hold shape. Beat the room-temperature cream cheese until perfectly smooth, then incorporate the cooled white chocolate and bright orange zest until the mixture is silky. Blend in the champagne so the mixture loosens slightly and smells floral, then fold in the whipped cream in two additions with a large rubber spatula, preserving the airy texture and leaving no streaks. Pour and spread this pristine, satin-white filling into the chilled crust, smoothing the top into a flat, reflective surface. Refrigerate the assembled cheesecake for at least four hours to set.

Whip a second small batch of heavy cream with a touch of powdered sugar to firm, pipeable peaks in the same chilled metal bowl; transfer to a pastry bag fitted with a large open star tip. Remove the set cheesecake from the springform, pipe an even ring of crisp, textured rosettes around the edge, and finish with delicate threads of fresh orange zest scattered across the top. Slice a clean wedge to reveal the distinct golden graham base and the airy, luminous white filling, and plate the slice on a white plate speckled with golden polka dots. Serve with a chilled flute of bubbly and a half orange nearby for garnish and aroma.
