Cranberry-Orange Sparkling Wine Gelatin

Place sugar and 2 1/2 cups of the cranberry juice in a medium saucepan; bring to a boil over medium-high, stirring to dissolve sugar. Add frozen cranberries; cook, stirring occasionally, until cranberry skins just start to split, about 6 minutes. Meanwhile, stir together 2 of the gelatin envelopes and remaining 1/2 cup cranberry juice in a small bowl. Let mixture bloom until thickened and swelled, about 3 minutes. Remove cranberry-sugar mixture from heat; stir in gelatin-cranberry juice mixture and gin until gelatin is completely dissolved.

Coat a decorative 12-cup Bundt pan with cooking spray. Pour cranberry-gin mixture into Bundt pan; let cool slightly, about 20 minutes. Cover and refrigerate until set, about 4 hours.

Strain juice from orange segments into a small saucepan (it should be about 1/2 cup); set aside orange segments. Bring orange juice to a simmer over medium. Meanwhile, stir together 1/2 cup water and remaining 3 envelopes gelatin in a small bowl. Let mixture bloom until thickened and swelled, about 3 minutes. Remove orange juice from heat; stir in gelatin-water mixture until gelatin is completely dissolved. Pour mixture into a large heatproof bowl or an 8-cup liquid measuring cup. Gently and slowly pour sparkling wine into gelatin mixture (if needed to avoid excessive bubbling, hold a spoon over bowl with its back curved side facing up, and pour wine over it so that it dribbles off both sides to more gently disperse). Alternatively, tilt bowl to let wine dribble down bowl sides. Gently stir in elderflower liqueur, avoiding agitating the bubbles.

Remove firmed cranberry gelatin from refrigerator. Arrange reserved orange segments over cranberry gelatin. Gently pour wine mixture into Bundt pan over orange segments (some segments may float). Chill until mixture is firm and set but still jiggles, at least 4 hours or up to overnight (12 hours). 

Remove gelatin mold from refrigerator. Quickly dip bottom of Bundt pan into a bowl filled with warm water (hold for about 10 seconds), and invert onto a greased platter or cake stand. Refrigerate, covered, until ready to serve or up to 3 days.