Step 1: Prepare the Pomegranate Base In a small saucepan, combine 1 cup of the pomegranate juice with the sugar and agar-agar powder. Whisk the mixture thoroughly while it is cold to ensure there are no clumps. Place the pan over medium heat and bring it to a gentle simmer, stirring constantly for about 3 to 5 minutes until the sugar and agar-agar are completely dissolved. Remove from the heat and stir in the remaining cup of cold juice to help cool the mixture down quickly.
Step 2: Whip the Cream In a large chilled mixing bowl, pour in the heavy whipping cream and the alcohol-free vanilla. Using a hand mixer or a stand mixer, beat the cream on medium-high speed until stiff peaks form. Be careful not to overbeat the cream, as you want it to stay smooth and velvety for the mousse texture.
Step 3: Combine and Fold Check the temperature of the pomegranate mixture. It should be cool to the touch but still liquid. Slowly pour the pomegranate liquid into the whipped cream while gently folding with a spatula. Use a light hand to keep as much air in the mixture as possible. Continue folding until the color is uniform and no white streaks remain.
Step 4: Fill the Molds Place a silicone semi-sphere mold tray on a flat baking sheet for stability. Carefully spoon or pipe the mousse into the cavities, filling them almost to the top. Smooth the surface with an offset spatula. Gently press a shortbread cookie onto the flat surface of each dome to act as the base. If the mousse is too soft, wait ten minutes before adding the cookie.
Step 5: Chill and Unmold Place the tray in the refrigerator for at least 4 hours, though overnight is best for the cleanest unmolding. When ready to serve, gently peel the silicone mold away from the edges of the mousse and press from the bottom to pop the domes out. Place them on a serving platter and garnish with fresh pomegranate arils and mint leaves.
