Preheat oven to 350˚F. Cube bread into about 1-inch cubes. Separate egg white and whisk until it is light and frothy. Add in bread cubes and stir to coat bread. Then add sesame seeds.
Spread bread out on baking sheet lined with parchment paper and bake for 15 minutes or until bread is very crispy.
For soup:
Using the saute function of your pressure cooker (or in a separate skillet), add olive oil and ground beef and cook until browned, breaking beef as it browns. Then add onion and garlic and cook for a few minutes until soft.
Add in potatoes, celery, carrots, beef stock, thyme, salt, and pepper. Seal pressure cooker lid and cook on high for five minutes. Then cancel the cooking and let cooker rest for 10 minutes. Release the steam from the pressure cooker.
In a separate pot, add butter and flour over low heat. Slowly whisk in milk until thickened. Add this light gravy to your soup to thicken it slightly.
Keep soup warm in the cooker and add cheese right before serving.
Serve the soup in big bowls topped with croutons, tomatoes, pickles, cheese, and parsley.