Preheat the oven to 400°F (200°C).
In a large bowl, toss the cauliflower florets with 3 tablespoons olive oil, minced garlic, 1 teaspoon kosher salt, and 1/2 teaspoon black pepper until evenly coated.
Spread the cauliflower in a single layer on a baking sheet and roast until tender and lightly charred, 20–25 minutes. Remove from oven and let cool slightly.
While the cauliflower roasts, bring a pot of salted water to a boil and cook the orzo until al dente according to package instructions. Drain in a colander, rinse under cold water, drain well, and toss with the remaining 1 tablespoon olive oil to keep the grains separate.
In a large bowl, whisk together 3 tablespoons extra-virgin olive oil, 3 tablespoons fresh lemon juice, 1 teaspoon honey, 1 teaspoon Dijon mustard, and salt and pepper to taste to make the dressing.
Add the cooked orzo, roasted cauliflower, sliced red onion, crumbled feta, and dried cherries to the dressing and toss until everything is well coated.
Fold in the baby spinach and toss gently until the spinach is slightly wilted and the salad is evenly combined. Taste and adjust seasoning with more salt and pepper if desired. Serve warm or at room temperature.
