Making Sourdough Pesto Grilled Cheese is straightforward if you follow these steps:

1. Prepare Ingredients: Gather all your ingredients. If using, slice the tomatoes or prepare any additional fillings.
2. Spread Pesto: Spread a thin layer of pesto on one side of each slice of sourdough bread.
3. Add Cheese: On the unspread side, pile a generous amount of shredded cheese.
4. Add Fillings (Optional): If desired, layer on sliced tomatoes or spinach atop the cheese.
5. Top with Bread: Place another slice of bread on top, pesto side out.
6. Heat Butter: In a skillet over medium heat, melt 1 tablespoon of butter.
7. Grill the Sandwich: Carefully place the sandwich in the skillet. Cook for about 3-4 minutes or until the bread is golden brown.
8. Flip the Sandwich: Add the remaining butter to the pan and carefully flip the sandwich. Grill the other side for an additional 3-4 minutes.
9. Check Cheese Melt: The sandwich is ready when the bread is crispy and the cheese is melted.
10. Slice and Serve: Remove from the skillet, slice in half, and serve hot.

Following these steps, you can easily craft the most delightful Sourdough Pesto Grilled Cheese!