To make the White Chocolate Panna Cotta: In a small bowl, sprinkle the gelatin over the water. Allow to sit as you prepare the remaining ingredients.
In a medium saucepan, whisk together the heavy cream, milk, and granulated sugar over medium heat. Stir often until the sugar is dissolved and the mixture begins to bubble on the edges. Remove from heat and add the white chocolate chips. Whisk until smooth, then stir in the white chocolate liqueur, vanilla extract, and gelatin with the water until smooth. Transfer among individual serving glasses (leaving room in each one for the strawberry layer), cover, and chill until set, 4 hours to overnight.
To make the Strawberry Gelatin: In a small bowl, sprinkle the gelatin over the water. Allow to sit as you prepare the remaining ingredients.
In a blender, puree together the strawberries and orange juice. Strain through a fine mesh sieve, pressing down with a spoon to get as much juice as possible, into a medium pot and place over medium heat. Stir in the granulated sugar and cook, stirring often, until the sugar has dissolved and the mixture is starting to bubble. Remove from heat and stir in the lemon juice, then the gelatin in water. Pour over the set white chocolate panna cotta, cover, and refrigerate until chilled, 4 hours to overnight.
To assemble: Top each glass with blueberries and mint leaves if desired and serve immediately.