Preheat the oven to 350°F (175°C). Grease and line a 9x13 inch baking pan with parchment paper.

In a mixing bowl, cream together the softened butter, granulated sugar, and brown sugar until light and fluffy.

Add the eggs one at a time, mixing well after each addition.

In another bowl, whisk together the flour, baking powder, and salt. Gradually add to the butter mixture until just combined.

Spread the batter evenly in the prepared baking pan.

Bake for 25-30 minutes or until a toothpick inserted in the center comes out clean. Allow to cool in the pan.

In a saucepan over medium heat, melt the granulated sugar, stirring constantly until it turns a deep amber color.

Add the butter pieces and stir until melted and combined.

Slowly pour in the heavy cream while stirring. Be careful as it may bubble up.

Remove from heat and stir in the sea salt. Allow to cool slightly.

Once the butter bars have cooled, pour the salted caramel over the top, spreading it evenly.

Allow the caramel to set for at least 30 minutes before cutting into squares.

Serve and enjoy your salted caramel butter bars!