Preheat the oven to 400 degrees F. Arrange the bacon slices side by side on a parchment-lined baking sheet and bake until browned and crisp, 15 to 18 minutes. Drain on paper towels.
Meanwhile, make the pistachio cream: Combine the pistachios, red pepper flakes, garlic, lemon juice and spinach in a food processor and pulse until chopped; with the motor running, slowly stream in the olive oil until incorporated. Season with salt and pepper and process 5 more seconds. Pour the mixture into a bowl and whisk in the crema; set aside.
Assemble the quesadillas: On 1 half of each tortilla, layer 1/2 cup cheese, 3 slices bacon and a few date slices. Fold the tortillas in half to cover the filling. Heat 1 tablespoon olive oil in a nonstick skillet over medium heat. Add 2 quesadillas and cook until golden on both sides and gooey in the middle, 4 to 5 minutes per side. Repeat with the remaining 2 quesadillas, adding the remaining 1 tablespoon oil to the pan.
Cut each quesadilla into 4 triangles; serve with the pistachio cream.