Preheat your oven to 350°F (175°C). Spread the chopped pecans on a baking sheet and toast them for 7–8 minutes, stirring occasionally, until fragrant and golden. Allow the pecans to cool completely before chopping them finely.

In a large mixing bowl, combine the softened unsalted butter, packed brown sugar, and white sugar. Cream them together on medium speed for about 3–4 minutes until light and fluffy.

Crack in the large eggs one at a time, mixing in the pure vanilla extract until well blended.

In a separate bowl, whisk together the all-purpose flour and baking soda until well combined.

Gradually add the dry ingredients to the butter-sugar mixture, alternating with buttermilk.

Gently fold in the toasted and chopped pecans using a rubber spatula.

Grease a Bundt pan or a 9x13-inch baking dish with butter. Pour the batter into the prepared pan.

Place the cake in the preheated oven and bake for 45–55 minutes. Check for doneness by inserting a toothpick into the center.

Remove the cake from the oven and let it cool in the pan for about 10 minutes. Transfer to a wire rack to cool completely.

In a saucepan over medium heat, combine the unsalted butter and packed brown sugar. Stir until sugar is dissolved and mixture comes to a gentle simmer.

Remove from heat, whisk in heavy cream, then gradually stir in powdered sugar until smooth.

Pour the frosting over your cooled Buttery Pecan Cake and sprinkle extra chopped pecans on top if desired.