Preheat your oven to 350°F (175°C).

In a large mixing bowl, sift together all-purpose flour, baking powder, baking soda, and salt.

In a separate bowl, beat together softened butter and granulated sugar until light and fluffy.

Incorporate eggs, buttermilk, vanilla extract, and melted butterscotch chips into the butter-sugar mixture.

Gradually add the dry ingredients into the wet mixture, mixing on low speed until just combined.

Pour the batter into your greased cake pan and bake for about 40 minutes.

Once baked, let the cake cool in the pan for about 10-15 minutes before transferring it to a wire rack.

In a mixing bowl, beat together softened butter, powdered sugar, butterscotch sauce, heavy cream, and vanilla extract until smooth.

Once the cake is cooled completely, frost it generously with butterscotch frosting and sprinkle with chopped pecans and crushed pretzels.