Melt 3 tablespoons butter in a non-stick pan over medium-high heat. Add pecans and cook 4-6 minutes, stirring often, until toasted. Remove from heat and cool.
Preheat oven to 350° F. Grease and lightly flour two 8-inch round cake pans. In a medium bowl, stir together flour, baking powder and salt. Set aside.
Beat ⅔ cup softened butter in a large bowl stand or hand mixer on medium-high for 30 seconds.
Reduce to medium, add sugar gradually, until well combined. Scrape bowl and beat 2 minutes more.
Add vanilla and one egg, beating until combined. Beat in remaining egg.
Reduce speed to low. Alternately add in flour mixture and milk and beat just until combined.
Fold in 1-cup of the toasted pecans, pour batter evenly into prepared pans. Bake 30-35 minutes, or until a toothpick inserted in center comes out clean. Cool pans on a wire rack for 10 minutes. Remove cake layers from pans and cool on racks to room temperature. Make the butter cream and decorate.
In a mixer, beat butter and vanilla on medium until light and fluffy. Reduce to low and slowly beat in 2 cups powdered sugar.
Beat in 3 tablespoons milk. Gradually beat in remaining powdered sugar and milk.
How to Decorate
Spread a thin layer of the buttercream onto the top of one cake layer.
Add the second cake layer evenly over the top. Frost sides and top with remaining buttercream until completely coated.
Sprinkle with remaining toasted butter pecans.
Greasing and flouring the cake pans prevents the cakes from sticking and makes removal easier. Or you could add a round cut-out piece of parchment paper to the bottom of the pan.
When making the buttercream the butter must be at room temp. This will make mixing easier, create the correct texture and help to avoid any lumps.
Add the powdered sugar to the butter slowly in the stand mixer to avoid a mess and incorporate evenly
Let the cake to cool completely before frosting or the frosting will melt
An icing spatula works best for spreading the buttercream. If you don’t have one a regular spatula would work.
If you don't have pecans, substitute with walnuts or hazelnut.
Once decorated the cake can be served immediately, but I find it's best to chill a bit in the fridge before serving to let the frosting firm up and make slicing easier. At least 30 minutes of chilling is recommended.
Leftovers must be stored in the fridge. Store cake in a sealed container in the fridge for up to 3 days for best flavor and texture.
When serving from the fridge: Let the cake sit at room temp for about 15 minutes before cutting and serving.