Wash and dry all produce. Trim and thinly slice scallions, separating whites from greens. Melt 1 TBSP plain butter in a small pot over medium-high heat. Add scallion whites and cook, stirring, until just softened, 1 minute. Season with salt.

Stir rice into pot with scallion whites. Add 3/4 cup water (11/2 cups for 4 servings) and a pinch of salt. Bring to a boil, then cover and reduce to a low simmer. Cook until rice is tender, 15-18 minutes. Keep covered off heat until ready to serve.

Meanwhile, zest and quarter lemon (for 4 servings, zest 1 lemon and quarter both). Trim ends from zucchini. Working over a large bowl, shave zucchini lengthwise into ribbons using a peeler, rotating as you go. Stop once you get to the seedy core; discard core.

Toss zucchini ribbons with basil oil and half the lemon zest. Season with plenty of salt and pepper. Add a squeeze of lemon juice to taste; toss to coat. Set aside. Rinse shrimp, then pat dry with paper towels and season all over with salt and pepper.

Heat a large drizzle of olive oil in a large, preferably nonstick, pan over medium-high heat. Add shrimp; sprinkle with a pinch of chili flakes if desired. Cook, stirring, until pink and cooked through, 3-4 minutes. Stir in garlic herb butter and a squeeze of lemon juice.

Fluff rice with a fork and season with salt and pepper; divide between plates. Shake off any excess marinade from zucchini ribbons, then arrange over rice. Top with shrimp and drizzle with any remaining sauce in pan. Garnish with scallion greens, remaining lemon zest, and chili flakes to taste. Serve with remaining lemon wedges on the side.