Preheat the oven to 350°F. Line a cupcake pan with cupcake liners.

Toast the pecans on a baking sheet for about 5 minutes, longer if the oven is not fully preheated. Cool the pecans and then chop into fine pieces.

In a large mixing bowl, combine the sugar, brown sugar, vegetable oil, eggs and egg yolks, and vanilla extract. Beat on medium speed until the eggs and oil are well incorporated and the batter is lighter in color, about 2 minutes. Scrape down the bowl as needed.

Next, mix in the sour cream and beat until well combined.

In a medium-sized bowl, combine all remaining dry ingredients. Then, add half the dry ingredients to the batter followed half the buttermilk and beat until it starts to combine.

Finally, add the remaining dry ingredients, mixing on low speed while pouring in the buttermilk and beating until all of the ingredients are well-combined.

Use a spatula to scrape down the sides of the bowl and stir the batter from the bottom to the top to ensure it’s well mixed. Add the chopped pecans and fold into the cupcake batter.

Cut the butter into pieces. Using the paddle attachment, whip butter for 5-7 minutes, scraping down the bowl occasionally. Beat until butter look light in color.

Add 3 cups of powdered sugar and mix on low speed until incorporated into butter then add the vanilla extract and mix to combine. Beat for about 60 seconds.

Next, add an additional 2 cups of powdered sugar and the brown sugar and maple syrup and beat on low speed until sugar is incorporated. Increase speed to medium-high and beat for 2-3 minutes.

Add the remaining powdered sugar and heavy cream. Beat on low until ingredients start to mix. Increase speed to medium-high and beat for another 2-3 minutes to whip additional air into the frosting. If the frosting is too thick, add an additional tablespoon of heavy cream and continuing beating until fluffy.

Frost the cooled cupcakes using a large open star tip and garnish with leftover crushed pecans. Store in an airtight container.