Preheat the oven to 320° F. On a floured work surface, roll out the Sweet Pastry Dough to d-inch thick with a rolling pin. Place the dough in a tart ring. Crimp the edges. Dock the crust by lightly pricking it all over with a fork. Chill the prepared dough in the refrigerator for 1 hour. Pre-bake this tart base for 8 minutes, then increase the oven temperature to 340° F and continue baking for an additional 10 minutes. Set aside to cool. Make the bergamot cream. Soften the gelatin in the juice of half a bergamot. Bring the rest of the bergamot juice to a boil. Add the butter to melt it. Using a whisk or hand-mixer, beat the eggs, the sugar, and the custard powder together until light and fluffy. Drizzle some of the heated bergamot juice into this mixture, mixing continuously, to temper. When the bowl is warm, add this mixture back to the pot and continue stirring to combine. When the mixture has thickened, add the gelatin. Cook for an additional minute, stirring constantly. Add the bergamot essential oil. Strain the cream through a chinois. Make the meringue. Place the egg whites in the bowl of a stand mixer or in a metal bowl. Beat with a stand mixer or hand-mixer until stiff peaks form. In a saucepan, heat the sugar with 7 tablespoons of water to 340° F; use a candy thermometer to monitor the temperature. Pour this hot syrup over the egg whites and continue beating until the mixture cools. Set aside. Spread the bergamot cream into the cooled tart shell. Set aside to cool completely. Using a spatula, spread the meringue over the cream. Use a kitchen blowtorch to lightly caramelize the surface of the meringue. Serve immediately.