Preheat the oven to 350 degrees Fahrenheit. Remove the wrappers from the chocolates. Discard the wrappers, and set the chocolates aside.
Add yellow cake mix, all-purpose flour, and salt to a large mixing bowl. Whisk to combine the ingredients.
In a separate mixing bowl, add creamy peanut butter, softened butter, light brown sugar, molasses, vanilla, and eggs. Whisk to cream the ingredients together, or use a hand mixer to blend them until creamy.
Add dry mixture (the cake mix and flour mixture) to the wet mixture (the peanut butter mixture) in small batches. Use a large spoon to fold in the dry mixture after each addition. A thick cookie dough will form. (If the dough is too thick, add 1 to 2 Tbsp of water and blend until the cookie dough just comes together).
Shape the cookie dough into 1-inch round balls. Roll each peanut butter cookie dough ball in granulated sugar to coat.
Next, place the cookie dough balls about 2 inches apart on the baking sheet. Bake the cookies for 9 to 10 minutes, or until the edges of the cookies just start to brown.
Remove the baking sheet from the oven, and immediately place a chocolate at the center of each cookie. (Use caution when placing the chocolates on the cookies, as both the cookies and the cookie sheet will be hot.) The cookies should flatten slightly and start to crinkle as you press the chocolate into the center.
Transfer the peanut butter blossoms cookies to a cooling rack to cool. Allow the cookies to cool completely before serving or storing them.