Place all romesco ingredients in blender - blend until smooth, taste and adjust seasoning if needed. Serve on crostini.
Preheat oven to 425 degrees. Prepare all ingredients. Place potatoes in a bowl and toss with 2 tsp Old Bay, salt, freshly ground pepper and olive oil - place on a parchment lined sheet pan, bake for 15 minutes. Remove from oven and turn potatoes. In the same bowl you tossed the potatoes - toss the sausage and garlic with some oil and 2 tsp Old Bay. Place on sheet pan with potatoes, return to oven and bake for 10 -15 more minutes. Check and remove from oven when desired crispiness of potatoes and sausage. Set aside and keep warm.
In the meantime melt the butter. Add 1 T Old Bay, 1/2 tsp smoked paprika, pinch of red chili flakes, 2 garlic cloves - minced, wine, lemon zest, salt and pepper to the butter, let cool. Brush some of the mixture on corn and toss the remaining with the leeks and cleaned shrimp. On another parchment lined sheet pan place the corn, leeks, and shrimp. Cook in oven for 5-8 minutes until shrimp are done, turn half way through, watch carefully not to overcook, they will turn pink when done. You may need to remove shrimp and return corn a few more minutes.
To serve: Arrange ingredients on one or two sheet pans, garnish with fresh squeezed lemon juice, chopped parsley and chives, or arrange on a large platter and garnish. Serves 4-6.