Butter each slice of bread on one side and set aside.
Using a cast iron skillet or non-stick skillet, over medium high heat, lay your first slice of buttered bread (butter side down) into the skillet and top with a ¼ cup of the grated Roth Havarti Chipotle and a 1/4 cup of the Roth Van Gogh Vintage Gouda. Cover the skillet with a lid and let the cheese melt until it's almost entirely melted, for about 3 to 4 minutes.
Next, lift the lid and top the melted cheese with some of the sautéed mushrooms and chard and cover again with the lid again for just a minute or two.
Take the second slice of buttered bread and spread dijon mustard* on the other side. Place the bread, dijon mustard side down onto the veggies (butter side out) and then flip your grilled cheese to begin toasting the other side. You do not need to cover the pan again since your cheese is already melting nicely. You can flip a couple more times if desired until you have nice, golden brown toasty bread on both sides.
Repeat everything for your second grilled cheese sandwich. Slice, serve and enjoy!