Pre-heat oven to 350° °F.
Slice zucchini into thin discs.
Bring medium pot of water to boil. Add zucchini and boil for 1 minute.
Blanch zucchini by removing zucchini and plunging into bowl of ice and water to halt cooking for 5 minutes.
Lay zucchini on layer of paper towels; pat dry exposed side.
Sprinkle zucchini with 1/8 tsp of salt, evenly distributed, to draw out moisture.
Heat medium size skillet over medium-high heat. Add 1 tsp olive oil.
Sauté onion and garlic until tender and translucent.
Add 1/2 cup grated cheddar, ½ cup fontina cheese, 1/4 cup whole milk, 1/8 tsp paprika, 1/8 tsp garlic powder, 1/8 tsp nutmeg , 1/8 tsp allspice, pinch of salt and 3 Tbsp chopped fresh spinach. Stir to combine.
Add 1 egg, stir and set aside.
Pat zucchini with paper towel to remove any liquid salt may have drawn out.
Spray pie plate with baking spray.
Line pie plate with sliced zucchini.
Pour cheese mixture on top.
Top with remaining 1/4 cup of cheddar cheese and 1/4 cup of fontina cheese.
Sprinkle with red pepper flakes, to taste.
Top with crushed cracker crumbs.
Cover loosely with foil and bake at 350°F for around 15-20 minutes until cheese is melted and bubbly.
Top with 1 tbsp sesame seeds and chives, as desired.