In a saucepan, combine heavy cream, whole milk, and 3 tablespoons of sugar. Heat over medium heat until sugar dissolves and mixture is warm. In a bowl, whisk together egg yolks. Slowly pour warm cream mixture into yolks, whisking constantly. Return mixture to saucepan, and cook over low heat until thickened. Stir in champagne and rose water. Chill mixture, then churn in an ice cream maker according to manufacturer's instructions.

Prepare Rose Meringue

Preheat oven to 225°F (110°C). In a clean bowl, beat egg whites until frothy. Gradually add 1 cup of granulated sugar, beating until stiff peaks form. Gently fold in cornstarch. Pipe meringue onto a parchment-lined baking sheet and bake for 1.5 hours until dry and crisp. Turn off the oven and let meringues cool inside.

Make Brioche Toast

Melt butter in a pan over medium heat. Toast brioche slices until golden brown on both sides. Remove from pan and set aside.

Candy the Rose Petals

In a saucepan, combine 1 cup of water and 1 cup of granulated sugar over medium heat until sugar dissolves. Dip fresh rose petals in the syrup, then lay them on a parchment-lined tray. Allow to dry for several hours until crystallized.