Prepare the Pecans:

• In a large skillet over medium heat, melt 3 tablespoons of butter. Once melted, add the chopped pecans.
• Cook, stirring constantly, until the pecans are toasted and fragrant, about 4-5 minutes. Be careful not to burn them.
• Remove the pecans from the heat and allow them to cool completely. Set aside.

Preheat the Oven:

• Preheat your oven to 350°F (175°C).
• Grease and flour three 9-inch round cake pans, or line the bottoms with parchment paper. This ensures that your cake layers will release easily from the pans.

Make the Cake Batter:

• In a large mixing bowl, beat the softened butter and granulated sugar together until light and fluffy, about 3-4 minutes.
• Add the eggs one at a time, beating well after each addition. Stir in the vanilla extract.
• In a separate bowl, whisk together the flour, baking powder, baking soda, and salt. Gradually add this dry mixture to the butter mixture, alternating with the buttermilk, beginning and ending with the flour mixture. Mix until just combined.
• Gently fold in the toasted pecans. Make sure they are evenly distributed throughout the batter.

Bake the Cakes:

• Divide the batter evenly among the prepared cake pans. Use a spatula to smooth the tops.
• Bake in the preheated oven for 25-30 minutes, or until a toothpick inserted into the center of the cakes comes out clean.
• Let the cakes cool in the pans for 10 minutes before transferring them to a wire rack to cool completely.

Prepare the Buttercream Frosting:

• In a large mixing bowl, beat the softened butter until creamy.
• Gradually add the powdered sugar, one cup at a time, beating well after each addition.
• Add 2-4 tablespoons of heavy cream, vanilla extract, and salt. Beat on high speed for 3-4 minutes until the frosting is light and fluffy. Adjust the consistency by adding more cream if needed.

Assemble the Cake:

• Place the first cake layer on a serving plate or cake stand. Spread a generous amount of buttercream frosting on top.
• Add the second layer and repeat the frosting. Top with the third cake layer.
• Frost the top and sides of the cake with the remaining buttercream. Smooth it out with an offset spatula for a clean finish.
• Garnish the top of the cake with whole pecans, if desired.

Serve:

• Refrigerate the cake for 30 minutes before serving to allow the frosting to set. This will make slicing easier.
• Slice and enjoy!