In a double boiler, melt together butter, sugars, cocoa powder and salt. Whisk together.
When all the butter has melted and everything is mixed together, remove the bowl from the heat and set aside to cool. It should be warm but not hot or it will scramble the eggs.
At this point, I poured the cocoa mixture into my stand mixer bowl and turned it on 2. Mix for 2 minutes. You can use whisk or wooden spoon.
Add vanilla and stir.
Add eggs, one at a time, beating well after each addition.
When your batter looks shiny, it's time to add flour. Add it all at once and beat until it disappears in the batter.
Pour the batter into your prepared pan and spread evenly.
Bake 25 - 30 minutes.
Cool completely before cutting.
!to make the ganache:
Place chocolate in a small mixing bowl.
Bring the cream, sugar and corn syrup to boil. Pour over chocolate. Do not stir. Let sit for at least 5 minutes. Stir until smooth. Pour over brownies. Let set for 3 minutes. Sprinkle with sprinkles. Arrange the chocolate hearts. Chill the brownies in the fridge until set, about 1 hour.