Preheat oven to 350 degrees. Line a cupcake tin with baking papers.
In a large mixing bowl, add in the butter and sugar. Mix on medium until light and fluffy. It should take about 2 minutes.
Add in the vanilla and eggs one at a time. Once the first egg is completely mixed in, add the second egg and mix until incorporated.
Mix in the buttermilk on low speed.
In a separate bowl, sift the cocoa powder, baking soda, baking powder, and quinoa flour.
Mix half of the flour mixture into the butter and sugar. Beat on low until combined.
Add in all of the hot water and continue to mix on low until combined.
Add the remaining flour and beat on low until incorporated.
Fill the cupcake liners three-fourth full. Place in the oven for 27-29 minutes or until the cupcakes are done. Place a toothpick in the center of the cupcakes. If it comes out clean or with moist crumbs, the cupcakes are done.
Let cool completely and start roasting the hazelnuts.
Roasted Hazelnut Paste
Preheat oven to 350 degrees.
Place the ¾ cup plus 2 tablespoons of chopped hazelnuts on a jelly roll pan or any pan with raised edges. Make sure they're spread out.
Let the hazelnuts roast for 10 - 13 minutes minutes until golden brown. Once you start smelling the nutty smells from the oven, they should be almost done or done. Let the hazelnuts cool.
Set aside the 2 tablespoons of roasted hazelnuts for the tops of the cupcakes.
Add the ¾ cup of hazelnuts in a food processor. Process on high until the hazelnuts are almost completely smooth.
Add in the powdered sugar and mix until the paste is smooth and the powdered sugar is incorporated.
Roasted Hazelnut Buttercream
In a large mixing bowl, add in all of the hazelnut paste. It should be about ½ cup. Mix until fluffy.
Add in the butter and continue to mix until incorporated.
Add in the vanilla, powdered sugar, and 1 tablespoon of milk. Mix on low until combined. Turn the mixer on high and mix for another 2 - 3 minutes until light and fluffy. If it needs more liquid, add the additional ½ tablespoon of milk.
Place the buttercream into a piping bag with a round tip or coupler. Pipe a nice dollop on top of each cupcake. Sprinkle the tops of the cupcakes with the remaining 2 tablespoons of hazelnuts.
Notes
With milk being in the buttercream you want to ensure that you store any leftovers in an air tight container in the refrigerator for up to 3 days.