Bring a large pot of salted water to a boil. Add the cauliflower florets and cook until fork-tender, about 10-12 minutes.
While the cauliflower is cooking, heat the olive oil in a small skillet over medium heat. Add the minced garlic and sauté for about 2-3 minutes until fragrant, being careful not to burn it.
Once the cauliflower is cooked, drain it well and return it to the pot.
Add the sautéed garlic and oil mixture, sour cream (or Greek yogurt), dried thyme, and dried rosemary to the pot with the cauliflower.
Use a potato masher or immersion blender to mash the cauliflower until smooth and creamy, adjusting the texture to your preference.
Season with salt and pepper to taste, mixing well.
Transfer the mashed cauliflower to a serving dish and top with chopped fresh chives for garnish.
Notes
For a lighter version, use Greek yogurt instead of sour cream.