Preheat oven to 400 F.
Combine rhubarb and honey in a baking dish and toss to combine.
Roast for 20 minutes, until tender.
Allow to cool then puree by pulsing in a food processor, blender or using an immersion blender.
Add butter, salt and puree to a stand mixer fitted with a whisk attachment and whip together until smooth and combined.
Spread on toast, biscuits, french toast, or pancakes!