Preheat oven to 350F. Line two baking sheets with parchment paper or silicone baking mats. Set aside.
In a large bowl, beat together the cake mix, peanut butter, eggs and vegetable oil until smooth and completely combined, about 2 minutes.
Place the white sugar in a small bowl. Use a 1 1/2 Tablespoon cookie scoop to portion out the cookie batter and roll the cookie dough balls in the white sugar until completely coated.
Place the coated cookie dough balls at least 3" apart on the prepared cookie sheets. Use a fork to press down in a hatch-pattern on the top of each cookie, flattening them in the process.
Bake for 10-12 minutes until lightly golden and spread out. Allow the cookies to cool for 2 minutes on the baking sheet.
For the peanut butter frosting, beat together the butter, peanut butter, icing sugar and cream in a small bowl for 2 minutes. Adjust the consistency with additional sugar or cream, as needed.
To assemble the cookies, spread 1 teaspoon of the peanut butter frosting on the underside of one cookie, then top with 1/2 teaspoon to 1 teaspoon of the strawberry jam. Sandwich the cookie with a second cookie.