To make the garlic scape pesto, combine your garlic scapes, parmesan-reggiano, pistachios and lemon juice in a food processor and process at a medium speed until they are roughly chopped. Continue to run the food processor and slowly pour your olive oil in through the opening of the lid on the food processor. Process until all of the ingredients are very finely chopped and beginning to become smooth. If the pesto seems a little thick add 2-4 Tbsp of water until the desired thickness is achieved. Finally stir in salt and pepper to taste.
Cut your baguette into 1/4” thick pieces and lightly brush 1 side with olive oil. Place this olive oil side down on a baking sheet.
Using a butter knife, evenly spread approximately 2 tsp of garlic scape pesto on each crostini and then sprinkle with grated mozzarella.
Bake your crostini in a 350º F oven for 8-10 minutes, or until the bottoms are golden brown and the cheese is bubbling on top. While the crostini is baking, dice and seed your tomatoes.
After removing the crostini from the oven, immediately top with diced tomatoes and serve with salt and fresh cracked pepper to taste.