Preheat your oven to 350°F (175°C).
Line a 9x9 inch baking pan with parchment paper, leaving some overhang on the sides.
Melt 3 tablespoons of unsalted butter in a medium mixing bowl and let it cool slightly.
Add 1 cup of sugar, 2 large eggs, and 1 teaspoon of vanilla extract to the melted butter and whisk until well combined.
Sift in 1 cup of all-purpose flour, 1/2 cup of cocoa powder, and 1/2 teaspoon of sea salt, then gently fold until just combined.
Fold in 1 cup of chopped dark chocolate and 1 cup of maraschino cherries.
Pour the brownie batter into the prepared baking pan and bake for 25-30 minutes.
Let the brownies cool in the pan for 10 minutes, then lift them out and cool completely on a wire rack before cutting into squares.