Heat a griddle or large pan on medium high heat until hot, then lower to just above simmering and let sit for 3 minutes.
Meanwhile, butter the outsides of your bread, spreading evenly to the edges. Place butter-side down and top one slice with Havarti cheese and the other with Nutella.
Place both slices butter-side down in pan and cover with a lid. This will help your cheese to melt without burning your bread. Keep an eye on the toasted-ness of the bread and the melted-ness of the cheese. It should take 3-5 minutes to grill, depending on the strength of your flame.
Just before taking the grilled cheese off the heat, spread the Nutella side with a spoonful of raspberry jam. Remove both slices from heat and sandwich together. Cut and serve immediately!