Preheat your oven to 300 degrees F and spray 2 mini muffin pans with non-stick spray or line with paper liners. You may also use 1 normal-sized cupcake pan. Set aside.
In a small saucepan, add the beer and bring to a boil over medium-high heat. Reduce the heat and let simmer for 8-10 minutes. Remove from heat and set aside.
Create a double boiler by placing a heat-safe bowl over a simmering pot of water, making sure the bottom of the bowl does not touch the water. To the bowl, add the butter, canola oil, chocolate chips and Nutella. Whisk frequently, until the butter and chocolate have melted and the mixture is smooth. Remove from heat, transfer to a large bowl and set aside to cool for a couple of minutes.
To the large bowl, add the beer, sugars, vanilla extract, sea salt and baking powder. Whisk until smooth. In another bowl, beat the 3 eggs together and then add them to the larger bowl. Whisk again until smooth. Now, fold in the flour until just moistened. Do not overmix.
Pour the brownie batter into your prepared muffin molds. Place in the oven and bake for 30-35 minutes or until a toothpick comes out clean. Remove from heat and set aside to cool completely, about 1 hour.
While your brownies are cooling, prepare the frosting. In a small saucepan, melt the butter over low heat. Whisk in the cocoa powder, beer and milk. Continue to whisk until the mixture has thickened slightly and the alcohol has cooked out, about 5-6 minutes. Remove the frosting from the heat and whisk in the confectioner's sugar until it has dissolved and no lumps remain.
Spoon the frosting onto the cooled brownie cups and garnish with sprinkles if desired. Serve immediately or store in an airtight container for 3-4 days. Enjoy!