Preheat your oven to 350 degrees F. Grease an 8-inch square baking pan and line it with parchment paper.
In a medium heatproof bowl, place the butter and bittersweet chocolate. Set this bowl on top of a small saucepan filled with barely simmering water, creating a double boiler. Stir occasionally until completely melted and smooth.
Once melted, remove the bowl from the heat and set it aside to cool slightly.
In a large bowl, whisk together the granulated sugar, dark brown sugar, eggs, and vanilla extract until the mixture is pale and fluffy.
With a rubber spatula, gently stir in the melted chocolate mixture. Make sure to combine it thoroughly.
Sift the flour and cocoa powder into the chocolate mixture, adding the flaked sea salt as well. Fold the mixture carefully until there are no visible streaks of flour remaining.
Now, gently fold in the chopped Rolo candies.
Pour the brownie batter into the prepared pan and smooth the top with a spatula.
Press the whole Rolo candies into the surface of the brownie batter, spacing them out evenly.
Bake in the preheated oven for about 25 to 30 minutes. Allow to cool completely in the pan before slicing.
