For the cauliflower: In a large saute pan over medium-high heat, add the olive oil and butter to melt. Once melted, add the cauliflower florets, a nice sprinkle of salt and cook until golden on the bottom, about 3 minutes. Give a good toss and let cook for 3 more minutes. Repeat tosses until most of the cauliflower is coated with the butter and golden on parts, about 4 tosses or so. Cauliflower should still be crunchy at this point, but tender enough to eat a smaller floret. Go ahead, take a bite! Then, pour the rest of the florets into a large bowl and quickly cover tightly with plastic wrap. Cook in batches if the florets won't fit into one pan.
While the cauliflower continues to steam in the bowl, make the sauce. In the same pan over medium heat, add the butter. Once the butter is melted, add the onions, curry powder, turmeric and season with salt. Cook until tender, about 5 minutes, and then add the garlic and cook a bit more. Once the garlic is fragrant, add the chicken stock and bring to a simmer. Cook until the stock is reduced by half, and then add the heavy cream and raise to a simmer. Cook until the sauce is reduced and thickened. With a slotted spoon, remove the cauliflower from the bowl and add to the pot. Raise the heat and simmer 5 minutes more. Serve warm.