Preheat oven to 325F.
Spray an 8x8 or 9x9 pan with cooking spray and line with parchment paper. Let paper extend over two sides for easy removal of brownies.
Melt bittersweet chocolate and butter together in a microwave safe container. Heat on high for 30 second, stir. Repeat. Let sit for a few minutes and stir again. Chocolate should be smooth and completely melted. If not, heat on 50% power for in 15 second intervals until melted.
Beat eggs and sugar together in a medium bowl with a fork.
Mix in salt and vanilla extract. Stir in melted chocolate mixture.
Stir in flour just until combined.
Stir in white chocolate chips, mini chocolate chips, and cherries.
Pour into prepared pan and smooth top.
Bake for 25-30 minutes or until center has set.