In a large skillet, heat a tablespoon of olive oil over medium heat. Add ground beef, cooking until browned and no longer pink, about 5-7 minutes. Drain excess fat and transfer beef to a bowl.

In the same skillet, add the sliced mushrooms and season them with salt, pepper, and garlic powder. Sauté for about 5-7 minutes until softened.

Return the browned beef to the skillet with sautéed mushrooms. Lower the heat to medium-low and stir in the shredded cheese, allowing it to melt into the mixture.

In a medium bowl, mix Greek yogurt, finely diced cucumber, minced garlic, and fresh dill together for the tzatziki sauce.

Warm pita pockets in the microwave for about 10-15 seconds or in a skillet over low heat for about 1 minute each side.

Open each warm pita pocket and spoon in the cheesy beef and mushroom mixture generously.

Add a generous spoonful of tzatziki sauce into each filled pita pocket. Serve immediately.