Transfer 1 cup frozen peas to a microwave proof dish, rinse under cold water, drain and cover with cling wrap and heat on high for 1-2 minutes, drain, rinse under to cold water to stop the cooking, drain again and set aside until ready to use.
Transfer10-12 whole snow peas to a microwave proof dish, rinse under cold water, drain, then cover with cling wrap and heat on high for 30 seconds. Drain and rinse under cold water to stop the cooking. Slice into thin slices, about 4 o 5 per snow pea, and set aside until ready to assemble tartine.
Reserve about 2-3 tbsp cooked and cooled peas and add to the remaining peas 2 large tablespoons of ricotta cheese , 2 tbsp grated parmesan cheese, 1/2 lemon zest and juice , salt and black pepper and 3 tbsp good quality olive oil to a food processor. Pulse and then mix until the topping is smooth and completely combined.