In a large bowl, whisk together egg, mayo, parsley, dill, Worcestershire sauce, dijon, garlic powder, old bay, lemon zest, and lemon juice.
Dump out lump crab meat on top then the cracker crumbs on top of the crab meat. GENTLY fold together everything until the sauce just coats the entire mixture. you don't want to stir or fold too much or you'll break up the crab meat.
Cover mixture and refrigerate for 30 minutes.
In the meantime, preheat oven to 450 °F (232 °C) and prepare homemade tartar sauce. Brush the surface of a rimmed baking sheet with 1 tbsp of the melted butter.
Once mixture has chilled for 30 minutes, using a 1/2 cup scoop, scoop mixture and put it onto the prepared baking sheet. DO NOT press flat. Literally just plop the mixture onto the baking sheet and use your hands to gently cup the cake into a mound to make sure no loose filling is on the side. Repeat until all mixture is used up. I usually can get 5-6 crab cakes.
Brush the tops of the crab cakes with the remaining melted butter. I don't actually forcefully brush but more like dab lol
Bake for 14 minutes or until the crab cakes are nice and brown on top.
Remove from oven and let cool for 5 minutes then assemble sandwich.
While crab cakes are cooling, toast brioche buns.
To assemble sandwich: place crab cake onto bottom bun, spread a generous amount of tartar sauce on top bun then top onto the crab cake. I like smashing it down a bit to flatten the crab cake a little.
Serve with a slice of lemon.
Notes
Very important: use lump crab meat not jumbo lump or claw meat, but lump. They usually come in 8 oz. containers so you'll need two containers.Also very important: do not use canned crab meat. It just doesn't bind as well and your crab cakes may fall apart. The best is to use fresh crab meat and you can usually find the containers at the seafood counter at your local grocery store.