First, toast your pecans: Preheat oven to 350 degrees F. Toss together the chopped pecans and melted butter and spread out evenly on a parchment-lined baking sheet. Toast the nuts for 5-10 minutes, watching carefully so they do not burn. They should smell nutty and fragrant. Remove from oven and cool the pecans until cool to the touch. Meanwhile, grease three 9" round baking pans and line with parchment rounds.
In the bowl of a stand mixer, cream the butter and granulated sugar together until fluffy, about 2 minutes. Beat in the eggs, one at a time, mixing well after each addition, followed by the vanilla and butter extracts. Meanwhile, in a medium bowl, whisk together the flour, baking powder, and salt. Gradually add in the flour mixture, alternating with the buttermilk, mixing well after each addition. Finish with the buttermilk.
Fold in 1 & 3/4 cups of the toasted pecans. Pour evenly among the pans. Bake for approximately 25-30 minutes or until a toothpick inserted near the center comes out clean or with moist crumbs. Cool completely and if cakes are too domed on top, use a serrated knife to gently remove the dome.
To make your frosting: In another bowl of your stand mixer, beat the butter, cream cheese, and vanilla together with the paddle attachment until creamy and combined, about 1 minute. Gradually add in the confectioners sugar, one cup at a time, beating well after each addition until frosting is light and fluffy. Only use the heavy cream/milk if frosting becomes too thick or pasty, nothing that you may not need it.
To assemble: place a cake layer on a cake stand or plate. Spread with some of the frosting and top with another cake layer. Repeat. Once your layers are assembled, frost the outside of the cake as best as you can, until smooth. Sprinkle the remaining toasted pecans around the perimeter of the top of the cake. Serve!