1. Heat 1/4 cup olive oil in a medium soup pot over medium-low heat. Add the onion and 1/4 teaspoon salt, and cook until the onion is soft and translucent, about 5 minutes (don’t let it brown).
2. Meanwhile, grate 4 garlic cloves on a microplane or crush them with a garlic press – these tools ensure the most intense garlicky flavor. Drain both cans of beans in a colander and rinse them under running water.
3. When the onions are ready, stir the garlic into the pot and cook for 30 seconds. Then add the beans and lots of black pepper, and stir to coat in oil. Cover the pot with a lid and cook for 5 minutes.
4. Next, add 3 cups broth and the broccoli to the pot, and bring the liquid to a boil. Then reduce the heat to low and simmer covered until the broccoli is cooked through but still bright green, 6 to 8 minutes.
5. Take the pot off the heat and add lemon juice. Using an immersion blender (see note below for standard upright blender instructions), purée the soup until it is mostly creamy but still has a bit of texture. Taste and adjust the seasonings if needed before serving.

To make the pumpkin seeds (optional):

1. Place the seeds in a small dry skillet over medium-low heat. Toast, tossing frequently to keep the seeds from burning, until they’re fragrant, lightly browned, a little puffed, and making a slight crackling sound, 4 to 5 minutes.
2. Turn the heat off, add the oil, and toss to coat. Then add the seasonings and toss to coat again. Cool completely before storing. (These seeds will keep in an airtight container in a cool dry place for up to 2 weeks.)