Hasselback Butternut Squash with beurre noisette mayonnaise

I first tried beurre noisette mayonnaise at a restaurant in Amsterdam: a wonderful creation in which the oil in the mayonnaise is replaced with beurre noisette, or “hazelnut butter” which is butter that’s melted and cooked over a low heat until it takes on the aroma, color, and flavor of hazelnuts. Store the mayonnaise in a cool place, but not in the refrigerator.