1-First Step: Begin by preheating your oven to 350°F (175°C). While the oven heats, prepare your mini cheesecake molds or silicone cups by lightly greasing them with butter or cooking spray. This will help ensure your shortbread bases release easily after baking.

2-Second Step: In a medium mixing bowl, combine the flour, powdered sugar, and salt. Cut in the softened butter using a pastry blender or your fingers until the mixture resembles coarse crumbs. The dough should hold together when pinched but still appear crumbly.

3-Third Step: Press approximately one tablespoon of the dough mixture into the bottom of each prepared mold, creating an even layer. Use the back of a spoon or your fingers to press firmly so the base will hold together when unmolded later. Place the filled molds on a baking sheet.

4-Fourth Step: Bake the shortbread bases for 10-12 minutes until lightly golden around the edges. Remove from oven and let cool completely while you prepare the mousse layer. The bases should be firm but not overbaked or they may become too hard to cut through easily.

5-Fifth Step: Place the cranberries and granulated sugar in a saucepan over medium heat. Add ¼ cup of water if using fresh cranberries to help them break down. Cook for 8-10 minutes, stirring occasionally, until the cranberries burst and become soft.

6-Sixth Step: Transfer the cooked cranberries to a fine-mesh sieve set over a bowl. Press the cranberries through the sieve with the back of a spoon to extract as much puree as possible. Discard the solids. You should have approximately 1.5 cups of cranberry puree. If desired, add the optional cranberry juice at this point.

7-Seventh Step: Sprinkle the gelatin over 2 tablespoons of cold water in a small bowl and let it bloom for 5 minutes. Meanwhile, return the cranberry puree to the saucepan and heat gently until warm but not boiling. Remove from heat and stir in the bloomed gelatin until completely dissolved. Let the mixture cool slightly but not set.

8-Eighth Step: In a separate chilled bowl, whip the heavy cream and vanilla extract until stiff peaks form. Be careful not to overwhip, which can cause the cream to separate. Gently fold one-third of the whipped cream into the cooled cranberry puree to lighten it, then fold in the remaining cream until no white streaks remain.

9-Ninth Step: Pour the cranberry mousse mixture over the cooled shortbread bases, filling each mold to the top. Gently tap the molds on the counter to release any air bubbles and smooth the surface with a spatula or the back of a spoon.

10-Tenth Step: Refrigerate the mini cranberry mousse cakes for at least 4 hours, or preferably overnight, until completely set. The gelatin needs time to firm up the mousse properly. Cover the molds loosely with plastic wrap to prevent any refrigerator odors from affecting the delicate flavor.

11-Final Step: To unmold, carefully dip the bottom of each mold into hot water for 3-5 seconds, then gently push up from the bottom or invert onto a serving plate. Garnish with fresh cranberries and mint leaves if desired. Serve chilled and enjoy these beautiful individual desserts that perfectly capture the essence of cranberry season.