Place a non-stick pan over the stove on medium-high heat and melt three tablespoons of butter. Then, add the chopped pecans. Afterward, cook for about 4 to 6 minutes and stir it often until pecans look toasted. Remove toasted pecans from the pan and the heat and let it cool.
After that, preheat your oven to 350 degrees Fahrenheit. Make sure to grease and lightly dust with flour the two 8-inch round cake pans. Afterward, set aside.
Next, stir together the baking powder, flour, and salt in a medium-sized bowl and set it aside.
Then, using an electric mixer, beat the 2/3 cup of softened butter on medium-high speed for about 30 seconds.
After that, gradually reduce the speed to medium and add the sugar gradually until everything combines well. Don't forget to scrape the bowl's sides. Afterward, beat for another 2 minutes.
Then, add the vanilla and one piece of egg to the mixture and beat until combined.
Afterward, fold in 1 cup of toasted pecans using a rubber spatula. Next, pour the cake batter evenly between 2 cake pans.
After that, bake the cake batter for 30 to 35 minutes until the cake cooks through.
Finally, please take out the cake pans from the oven and let them cool for about 10 to 15 minutes. Likewise, please take out the cakes from the pans and cool them on a wire rack at room temperature.