In a medium sauce pan, melt butter over medium heat. Once butter has melted, add cocoa and stir. Once cocoa is fully incorporated, add the granulated sugar and stir.
Continue to stir until the sugar begins to dissolve, approximately 2 minutes. Remove from heat and allow to cool for 10 minutes.
Preheat oven to 350°F. Line a 9x9 baking pan with parchment paper. Set aside.
Pour the butter mixture into a large mixing bowl. Add eggs and vanilla extract. Stir using a whisk until smooth. Add salt and all-purpose flour. Whisk until just incorporated. Gently fold in mini eggs.
Pour brownie batter into the prepared baking pan. Bake for 22-25 minutes.
While the brownies are baking, add the chocolate chips to a heat safe bowl. In a medium saucepan, bring whipping cream to a light simmer over low heat. Pour hot whipping cream over chocolate chips and allow to sit for 5 minutes. Add vanilla extract and salt, and whisk until smooth. Lightly cover and set aside.
Remove brownies from oven and allow to cool completely. Once the brownies have completely cooled, frost them with the ganache topping. Sprinkle extra mini eggs onto the brownie. Slice and serve!
It's normal that your brownies don't look fully set in the centre when you remove them from the oven. Don't panic, they will set at they cool.