Start by heating a skillet on medium-low heat. Add in the canola oil, and bring it up to temperature.
Add in the kale and the mushrooms, and cook until the kale is nice and tender, about 15 minutes. Stir periodically.
When the kale and mushrooms are softened, remove and place them in a bowl, and wipe out the skillet.
Return the skillet to the stove on medium-low heat, and add in the flour tortilla. Top with about 3/4 of the white cheddar cheese, then scatter the kale and mushrooms over the top. Place any remaining cheddar cheese on top of the mushrooms and kale.
Slowly cook the quesadilla until the tortilla gets nice and crisp and golden, and the cheese fully melts. Feel free to place a cover on the skillet to assist with melting the cheese.
When the cheese is fully melted, plate and serve.