Basil Pesto Freezer Cubes

From the garden

• 6 cups fresh basil leaves, packed, washed and dried very well
• 3 cloves garlic
• ½ cup walnuts or pine nuts, lightly toasted

From the pantry

• 1 cup olive oil — plus a little extra for topping the cubes
• ¾ cup finely grated parmesan (optional) — classic, but many cooks freeze the pesto without cheese and stir it in fresh after thawing
• salt — to taste

1. Wash the basil and dry it completely in a salad spinner and on towels — clinging water makes icy, dull cubes. Toast the nuts in a dry skillet over medium heat, tossing, 3–4 minutes until fragrant, and let them cool.
2. Pulse the garlic and nuts in a food processor until finely chopped. Add the basil and a good pinch of salt and pulse in short bursts, scraping down the sides, until finely chopped but still bright green — not a purée.
3. Pulse in the olive oil in two or three additions until the pesto is spoonable but still has texture. Stir in the parmesan, if using, and season — it should taste bold and a touch too salty straight, since freezing mutes flavor slightly.
4. Spoon the pesto into two ice-cube trays, pressing it into the corners, and slick the top of each cube with a thin film of olive oil to keep the surface green.
5. Freeze until solid, at least 6 hours, then pop the cubes into a freezer bag, press out the air, and label. Each cube is about 2 tablespoons — two or three sauces a serving of pasta.