Preheat your Traeger Flatrock to medium heat.
Slice King's Hawaiian Slider buns in half.
In a bowl, combine the eggs, cream and vanilla and whisk until well blended.
Dip the bun slices in the mixture.
Melt butter on the Flatrock and place the dipped buns on the melted butter.
Cook until golden brown, and then flip to continue cooking.
Meanwhile, place the thinly sliced ham on the griddle to begin heating.
When the French toast is cooked on both sides, transfer the bottom back to the Kings' Hawaiian paper tray.
Top the bottom rolls with the heated ham and then a layer of Swiss cheese.
Place the top bun on the cheese.
Place the entire sandwich stack back on the griddle, turned down to low, and close the lid.
Cook until the cheese is melted and bubbly.
Remove from the grill and allow to cool slightly before slicing.
Dust with powdered sugar and serve.