In a large pot, boil water and add pasta. Cook until just underdone, then strain and add back to pot. Toss with crab meat and set aside.
In a small bowl, melt 1 Tbsp butter, then add the panko and half of each of the following ingredients: lemon zest, parsley, old bay, and dill. Toss all together
In a medium saucepan over medium-high heat, melt the remaining 2 Tbsp of butter. Add the flour and whisk, cooking until light golden brown.
Slowly add the milk to the pan, whisking continuously to prevent scorching. Bring to a simmer and let thicken, approx. 5-7 minutes.
Remove from heat and add in remaining lemon zest, parsley, old bay, and dill. Stir in cheese until melted. Then season with salt and pepper.
Place the pasta-crab mixture in a baking dish, stir in cheese sauce, then top with panko mixture. Bake for 20 minutes, then broil a few minutes until top is nicely browned.