Preheat oven to 300 F. Put a wire rack on a cookie sheet and spray the rack with oil.
Melt butter in large frying pan over medium heat. Add minced shallots and 1/2 tsp. salt. When shallots are soft, add garlic and thyme. Saute another 30 seconds.
Add panko and 1/4 tsp. black pepper. Stir and "toast" for about 5 minutes.
Toast till panko is golden brown. Add parsley and place in a shallow dish to cool.
Whisk egg yolk, mayo, 1/4 tsp. black pepper, and lemon zest.
Dry fish and season with salt and pepper.
Paint the top of each piece of fish with the egg-mayo mixture. Place fish in bowl of panko, painted side down. Press to adhere to panko.
Distribute remaining panko on tops of fish. Place fish on the wire rack. Bake till fish registers 135 F. (30 - 40 minutes).