Heat olive oil in a pan over medium heat. Add onion and pepper (if using) and saute until onions are tender (approx. 7-10 minutes), stirring frequently.
Add half of the jalapeños, half of the garlic, coriander, cumin salt and pepper to the pan and continue to cook until jalapeños have softened (approx. 2-4 minutes). Remove from heat.
Spread 1-2 tablespoons of Mexican crema or cream cheese on each tortilla.
Divide onion and pepper mixture between 4 of the tortillas. Top with remaining tortillas.
Add diced tomato, diced jalapeno, onion, a dash of olive oil and mix together in a bowl.
Heat 1/2 teaspoon of butter in a pan over medium heat. After it has melted, add 1 quesadilla to the pan. Cook until the bottom is browned and crispy (approx. 2-4 minutes). Flip and cook until the other side is browned and crispy. Remove from the pan.
Add additional butter to the pan and repeat with remaining quesadilla.
Slice, top with tomato salsa, and drizzle with remaining Mexican crema. Serve immediately.