Preheat oven to 350F. Line a 10-inch cast iron skillet with aluminum foil and grease with non-stick cooking spray. Set aside.
In a large bowl, add 1 cup sugar and melted butter. Stir to combine.
Beat in the eggs, one at a time, using an electric hand mixer or stand mixer with fitted paddle attachment.
Add flour, 1/2 cup at a time, followed by salt. Add almond extract and stir well.
Pour batter into prepared skillet. Top with remaining 1 tablespoon of sugar and sliced almonds.