Begin by peeling the butternut squash and cutting it into approximately 1½-inch cubes. In a large pot, combine the cubed squash with peeled garlic cloves and cover with water. Bring to a rolling boil over medium-high heat, then reduce heat to a simmer and cook for 10-15 minutes, or until tender.

Carefully drain the squash and garlic in a colander. Return the mixture to the pot over low heat to evaporate excess water.

Add in the butter and olive oil. Mash the ingredients together with a potato masher, or use an immersion blender for a smoother texture.

Taste and add sea salt and black pepper according to preference. Stir well to evenly distribute the seasoning.

Transfer to a serving bowl and sprinkle with freshly chopped chives. Serve warm.