Melt dark chocolate with coconut oil in a heatproof bowl over simmering water or microwave in 30-second intervals, stirring until smooth.
Spoon 1 to 2 tablespoons of melted chocolate into silicone dome molds and spread evenly with the back of a spoon or brush.
Freeze the molds for 10–15 minutes until the chocolate shells set, then add a second thin chocolate layer and freeze again.
In a small saucepan, combine raspberries, sugar, and lemon juice and cook over medium heat for 4–5 minutes until berries break down.
Strain the cooked raspberry mixture through a fine mesh sieve to remove seeds and cool completely.
Whip cold heavy cream until soft peaks form, then add powdered sugar and vanilla and whip to medium peaks.
Gently fold the cooled raspberry puree into the whipped cream until smooth and light pink.
Fill the frozen chocolate shells with raspberry mousse using a spoon or piping bag and smooth the tops.
Freeze filled domes for at least 2 hours until firm.
Carefully remove domes from molds and place on a serving plate.
Pipe a small swirl of whipped cream on top and garnish with a fresh raspberry and a mint leaf.
Lightly dust powdered sugar around the dome bases for a bakery-style finish.