Peanut Butter Semifreddo Recipe

Name: Peanut Butter Semifreddo Recipe
Ingredients: For the Semifreddo:; 9 egg yolks; 1/2 cup plus two tablespoons sugar; 1/4 cup water; 3/4 cup peanut butter; 3/8 teaspoon kosher salt; 3/4 teaspoon vanilla extract; 1 1/2 cups cream, whipped to soft peaks and refrigerated; For the Hot Fudge; 2 1/4 oz. unsweetened chocolate; 2 tablespoons butter; 1 tablespoon + 1 teaspoon light corn syrup; 3/4 cup cream; 1 1/3 cups dark brown sugar; 1/2 teaspoon vanilla extract; 1/4 teaspoon kosher salt; Garnish: sea salt (optional)