Grab 20 slices of bread and slice off the crust edges. Grab one slice and roll out with a rolling pin until flat. Spread with 2 teaspoons of raspberry jam. Roll up tightly. Repeat with the other 20 slices.
In a medium bowl, mix heavy cream, salt, and eggs. Mix together with a fork in a whisking motion to beat the eggs well.
Place nonstick skillet over medium heat. Add 1 tablespoon of butter. While the pan heats up, dip a roll into the batter. Remove roll from custard and let the excess drain off. Then, place seam side down on hot skillet. Cook until the bottoms brown, about 1-2 minutes. Flip and cook 1-2 minutes more. Repeat with the rest of the rolls.
Add granulated sugar to a shallow bowl. Add French toast rolls to the sugar and roll to cover in sugar. Serve immediately.