Preheat the oven to 350°F. Lightly coat a 1 quart baking dish with cooking spray. Set aside.
Place the drained artichokes, beans, sour cream, onions, salt and lemon juice in the blender.
Select Auto 5 and blend until the mixture is chunky-smooth. Scrape down the sides of the blender, if needed, and pulse as needed.
Spoon mixture into the prepared dish and sprinkle the grated cheese over the top. Bake for 20 minutes, or until bubbly around the edges of the dish. Serve while warm with crostini.