Preheat oven to 425°F.
For the mayo, place egg yolks in a mixing bowl with the lemon zest and juice, and Dijon mustard. While whisking, slowly stream in the grapeseed oil until emulsified.
Line a baking sheet with parchment paper. Arrange chicken or fish on the baking sheet and season with salt and pepper. Slather 3 to 4 tablespoons of lemon mayo over the chicken or fish (store remaining lemon mayo in the fridge or use for Lemon Tuna Salad) and top with cheese combined with breadcrumbs. Bake until cooked through and breadcrumbs and cheese are golden brown.
Serve with shredded basil or chopped parsley with lemon wedges alongside and
roasted green beans, cherry tomatoes and garlic or roasted broccolini with chilies and garlic; both dressed with olive oil, salt and pepper and roasted until tender and browned at edges.
Use this method to cook chicken or fish, as little or as much as you need.