Toast the almonds in a pan over medium heat until golden brown, 2 to 3 minutes.
Spread one slice of the sourdough bread with a thick layer of the chocolate-hazelnut spread. Spread the other slice of bread with the marshmallow creme. Layer the strawberries onto the chocolate-hazelnut spread and top with a sprinkling of almonds. Then place the other slice of bread on top, marshmallow creme-side down. Press the 2 slices together.
Butter one side of the sandwich and put it on a hot panini maker butter-side down. Butter the other side, close the lid and cook until the sandwich is toasted and warmed through. (If you do not have a panini maker, you can grill the sandwich in a skillet, laying another heavy skillet on top of the sandwich to press it together. Turn to grill the other side in the same way.)
Sprinkle with powdered sugar, cut in half and serve!