Place cauliflower florets and whole garlic cloves in microwave steamer basket.
Add water to bottom of steamer basket and microwave on high for 8-10 minutes, until cauliflower is fork tender.
While cauliflower cooks, melt butter in a medium saucepan over low heat. Cook butter until it starts to foam and begins to brown. Swirl pan often to mix butter.
When you see the brown solids forming in the bottom of the pan, remove from heat and set aside.
Swirl the butter again and a little butter (about 1 tablespoon) to use as a drizzle over top of the cauliflower in the serving bowl.
Place cooked cauliflower in food processor with additional salt and black pepper (if using).
Process cauliflower mixture until it has a smooth and creamy texture.
Spoon garlic mashed cauliflower into a serving bowl and drizzle with reserved butter.