Preheat your oven to 350°F (175°C). Grease and flour two 8-inch round cake pans, or line with parchment paper.
In a large bowl, whisk together the sifted cake flour, granulated sugar, baking powder, and salt.
Add the softened butter pieces to the dry ingredients. Mix on low speed until the mixture resembles coarse crumbs and the butter is fully incorporated, about 2-3 minutes.
In a separate medium bowl, whisk together the eggs, buttermilk, and vanilla bean paste until well combined.
Gradually add the wet ingredients to the dry mixture, mixing on medium-low speed until just combined. Be careful not to overmix.
Divide the batter evenly between the prepared cake pans.
Bake for 30-35 minutes, or until a wooden skewer inserted into the center comes out clean.
Let the cakes cool in the pans for 10 minutes before inverting them onto a wire rack to cool completely.
While the cakes cool, prepare the frosting: In a large bowl, beat the softened butter with an electric mixer until light and fluffy.
Gradually add the sifted powdered sugar, one cup at a time, beating until smooth after each addition.
Add 2 tablespoons of heavy cream, vanilla extract, and a pinch of salt. Beat on high speed until light and fluffy. Add more cream, one tablespoon at a time, until desired consistency is reached.
Once cakes are completely cool, frost and decorate as desired.