Prepping the blueberries:
Whip ½ cup cream (at low speed) for 2-3 minutes until creamy and smooth. Add 2 tablespoons powdered sugar.
In a blender, place the fresh blueberries and turn them into a pulp. Transfer to the whipped cream and stir until evenly incorporated.
Making chocolate mousse:
In a stainless-steel mixing bowl, using an electric handheld mixer, whisk 4 egg yolks with ½ cup of sugar until the texture thickens. Make a "double boiler" (a pot filled with hot water, covered with a piece of cloth) and place the bowl filled with whisked eggs on top). Continue whisking the eggs at full speed for about 3-4 minutes. Check the temperature of the eggs; they should feel warm to the touch. Remove from the double boiler, add the vanilla extract. Continue whisking at full speed for about 5 minutes. Make sure the eggs are whisked for a long time, so the mousse is light and airy.
On the same "double boiler", place a stainless-steel bowl filled with 8 ounces semi-sweet chocolate chips. Add ¼ cup whipping cream. Slowly melt, stirring frequently.
Pour the melted chocolate into the egg mixture. Mix well. Add the blueberry mixture; using a silicone spatula, stir well until the color is uniform.
Whip the remaining heavy cream (at low speed) and salt for 2-3 minutes until creamy and smooth. Add 2 tablespoons powdered sugar. Increase to maximum speed and keep beating for another 2-3 minutes, until it forms soft peaks. Do not over-beat or the texture will become grainy.
Repeat the same procedure as with the egg mixture previously. Pour ½ the whipped cream into the chocolate mixture. Mix well until well combined. Pour in the rest of the whipped cream; using the silicone spatula, gently fold the cream into the chocolate to get an airy mousse.
Plastic-wrap the bowl and chill in the refrigerator until the rest of dessert is ready to assemble. The fat from the cream could pick up some other food odor from the refrigerator, so be sure the bowl is sealed properly.
Place 3 pretzels on an individual serving plate next to each other as the base of the dessert. Spoon ⅛ of the chocolate mousse mixture onto the pretzels. Decorate the sides of the dessert with more pretzels. Level the filling with a spatula (if necessary). Cover with a tall bowl, making sure the walls of the bowl don't touch the dessert and place in the refrigerator until you're ready to serve.
When you're ready to serve, top the dessert with a "quenelle" of vanilla yogurt, mascarpone or vanilla ice cream: using 2 teaspoons, gather one portion of the mixture in one spoon. Scrape the loose mixture from the sides using the other spoon. Repeat between the 2 spoons until the mound is tightly packed. Slide the mound onto the top of the dessert and decorate with a chocolate-covered blueberry as a reminder of the flavor of the mousse. Dust with powdered sugar.
I use Guittard extra semi-sweet baking chocolate chips that I buy directly from a local market.
For this particular dessert, I prefer a denser mousse so the pretzels don't fall apart. If you like a lighter, fluffier dessert, increase the amount of whipped cream.
You can find blueberry yogurt covered pretzels and dark chocolate-covered blueberries at theFruitCompany.com.