Remove the outer leaves and thick core from the cauliflower and cut the head into florets. Rinse, if needed, and dry thoroughly.
Working in batches as needed, add the florets to a food processor and pulse in short bursts until they resemble coarse grains of rice. Avoid overprocessing, which can make the cauliflower too fine and cause it to cook unevenly. Measure 2½ cups cauliflower rice for the recipe and reserve any remaining cauliflower rice for another use.
Heat the extra-virgin olive oil and butter in a 10-inch skillet over medium heat. Add the shallot and cook for 1–2 minutes, stirring occasionally, until softened but not browned. Add the garlic and cook for about 30 seconds, until fragrant.
Increase the heat to medium-high. Add the 2½ cups cauliflower rice, kosher salt, and black pepper and toss to coat. Spread into an even layer and cook uncovered for 5–7 minutes, stirring occasionally, until tender with some lightly golden bits. Avoid stirring constantly so the cauliflower has an opportunity to brown rather than steam.
Remove the skillet from the heat. Add the lemon juice and parsley and toss to combine. Add the lemon zest, if using. Taste and adjust the salt, black pepper, or lemon juice as needed. Serve immediately.
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Notes
Freezing extra cauliflower rice: If you have uncooked cauliflower rice remaining after measuring the 2½ cups needed for the recipe, transfer it to a freezer-safe bag, remove as much air as possible, and freeze for up to 3 months. Cook directly from frozen without thawing, allowing a little extra time for the excess moisture to evaporate.Cooking NotesDry the cauliflower well and use short pulses in the food processor so it stays coarse rather than turning into fine crumbs. Once it's in the skillet, cook it uncovered and stir only occasionally so excess moisture has time to escape.Tips for Best Results
Process the cauliflower in short pulses and stop when it resembles coarse grains of rice.
Measure 2½ cups after processing so the 10-inch skillet isn't overcrowded.
Cook uncovered so excess moisture can evaporate.
Add the lemon and parsley off the heat to preserve their fresh flavor.
How to Know It’s ReadyThe cauliflower should be tender but not mushy, with no excess liquid in the skillet and a few lightly golden pieces throughout.