Using paddle attachment, whip the butter until fluffy, scraping down sides of bowl as needed. With mixer on low, gradually drizzle in the syrup. Add zest, then increase speed to medium and whip for another minute or so.
You can also just whip it by hand, which sounds both kinky and exhausting.
Cutting butter into bits and letting it sit at room temperature helps it soften faster.
My favorite 4 oz measuring glass broke, so I'm left with a smaller 2 oz glass. It's perfect for measuring things like honey, ketchup, soy sauce and oils. I love having this thing in my kitchen!
Once the softened butter has been whipped, slowly drizzle in the maple syrup. It's very important that the butter and syrup be nearly the same temperature. You don't want the syrup to crystalize.
Lastly, beat in the orange zest. Be sure to taste a bit.