Preheat your oven to 350°F. Spray the bottom of a 9-inch cake pan or springform pan with cooking spray, line it with parchment paper, and spray again, ensuring you coat the sides this time. Set aside.
In a medium-sized bowl, whisk together the flour, salt, and baking powder.
1 teaspoon salt, 1 ½ cups all purpose flour, ½ teaspoon baking powder
In a large mixing bowl, using an electric hand mixer, cream the butter and sugar on high speed for 3 minutes.
8 Tablespoons unsalted butter, ¾ cup granulated sugar .
Add the eggs one at a time, whisking for 30 seconds after each addition. Add the vanilla extract and mix on low just until combined.
2 large eggs room temperature, 1 teaspoon pure vanilla extract
Add the buttermilk, then use a rubber spatula to fold the dry ingredients into the wet ingredients until no streaks of flour remain.
½ cup buttermilk
Pour the batter into the prepared cake pan and use the back of a spoon to gently spread it to the edges. Set aside while you make the cream cheese filling.
For the Cream Cheese Filling
In the same medium-sized bowl, use a hand mixer on medium-high speed to mix the cream cheese until smooth and creamy.
8 ounce cream cheese room temperature
Add the egg and mix on high for 30 seconds. Use a rubber spatula to scrape down the sides and bottom of the bowl.
1 large eggs room temperature, 3 cups powdered sugar
Add the powdered sugar, one cup at a time, mixing on the highest speed for 30 seconds after each addition. If add the butter extract do it now! This should take just over a minute.
¾ teaspoon butter extract
Once combined, pour the cream cheese mixture over the cake batter and use a small offset spatula to spread it into an even layer.
Baking & Serving
Bake for 45-48 minutes. The center will still be slightly jiggly, but the cake is done when the edges are golden and show slight cracking.
Turn off the oven and prop the door open for 10-15 minutes.
Remove the cake from the oven and let it cool completely to room temperature (about two hours).
Serve at room temperature. Store in the fridge, covered with plastic wrap or in an airtight container.