Preparation

• Test the accuracy of your candy thermometer by putting it in a small pot of boiling water. If it doesn’t read exactly 212°F, factor in the difference in the next step.
• Set the frozen chunks of butter beside the stove. Put the syrup in a 3-quart or larger stainless-steel saucepan and rub the inside rim with a bit of butter to prevent boilovers. Boil the syrup over medium heat without stirring until a candy thermometer registers 234°F (or the recalculated temperature, if your thermometer is off), 8 to 10 min. once the syrup boils; tilt the pan so the syrup covers the thermometer bulb to get an accurate reading.
• Take the pot off the heat and add the butter and salt, stirring constantly with a wooden spoon until the butter melts completely. Pour the syrup into the bowl of a stand mixer. Beat with the paddle attachment on medium-high speed until it’s cool, lighter in color, and creamy, 5 to 10 min. Pour the maple butter into jars or plastic containers, seal, and refrigerate. It will thicken as it cools and might get a little grainy. It lasts in the fridge or freezer as long as plain butter.