01 - 
                Warm a big skillet on medium-high. Toss in butter and olive oil, wait till butter melts completely.
              
              
              
                02 - 
                Put mushrooms flat in pan (work in small batches if crowded), sprinkle with ¼ tsp salt. Leave them alone for 3 minutes to get a nice sear.
              
              
              
                03 - 
                Turn mushrooms over and let cook another 2-3 minutes until they're nice and brown, don't stir too much.
              
              
              
                04 - 
                Lower heat to medium-low. Throw in garlic and more oil if pan seems dry. Add half the spinach, cover for 30 seconds, stir it up, then add leftover spinach, cover another 30 seconds.
              
              
              
                05 - 
                Sprinkle in the rest of your salt and squeeze in lemon juice, mix everything together. Dish it up right away.