Preheat the oven to 375 degrees F. Line 1 or 2 baking sheets with foil. Cut the pita rounds into eighths. Split each piece in two and place on the prepared baking sheets, with the inside of the bread facing up. Spray (or drizzle) with olive oil and sprinkle with 2 tsp. of the Greek seasoning. Bake 7-10 minutes or until golden.
Meanwhile in a large skillet, brown the ground lamb with the garlic salt and the remaining 2 tsp. Greek seasoning. Drain and set aside.
In a shallow 1 1/2 quart (clear) dish, spread the hummus on the bottom. Top with a layer of ground lamb, then the tzatziki. Layer with the lettuce, tomatoes, onion, olives and feta. Serve the dip at room temperature with pita chips.