Bulletproof Coffee in a Blender

Use an immersion blender in a tall, narrow mug, with the bell fully under the surface before you switch on. Ten to twenty seconds gives the emulsion — the pale, foamy, latte-like result — that stirring cannot. Do not use a sealed personal-blender cup: the coffee is near boiling, NutriBullet’s manual says no, and steam pressure under a clamped lid is the mechanism behind blender burns. A full-size jar works if it is vented, underfilled and started slowly, but it is a lot of machine to wash for one cup.

Why it has to be blended, and why that is the problem

Butter coffee is hot coffee, a tablespoon or two of butter and usually a spoon of MCT or coconut oil. Stirred, the fat melts and floats as a slick. Blended, the fat is broken into droplets small enough to stay suspended in the coffee, which is an emulsion — the same physics as a vinaigrette or hollandaise, and the reason the result is creamy rather than greasy. The blades do the emulsifying; there is no substitute.

The problem is temperature. Coffee comes off the brewer close to boiling, and a blender vessel with a sealed lid is a pressure vessel the moment hot liquid starts giving off steam inside it. Every rule on this page follows from that one fact, and the general version is set out in blending hot liquids safely.

What the manuals actually say

Sealed personal-blender cups: no

A NutriBullet, Magic Bullet, Ninja Blast or Beast cup screws shut and blends inverted or sealed. NutriBullet’s manual says the cup is not for hot liquid, and our catalog entry for the NutriBullet Pro repeats it. There is no vent, so there is nowhere for the steam to go except past the seal or through the lid when it is opened. This is the single most common way people try to make butter coffee and the one way that should never be used. The full explanation is in can personal blenders handle hot liquids.

Full-size jars: yes, vented and underfilled

Vitamix’s VX1 manual sets a 210 °F ceiling for the container, which is below boiling and which fresh coffee can exceed. The rules that make a jar safe are the standard ones: fill well below the line, remove the lid’s center cap so the vessel is vented, cover the opening with a folded towel, and start on the lowest speed. Done that way, the tall Vitamix container makes an excellent emulsion. It is also a 64 oz jar to wash for a 12 oz drink, every morning.

Immersion blenders: yes, and it is what they are for

A stick blender has no sealed vessel. You blend in the open mug, so there is nothing for pressure to build inside, and the same structural fact that makes it the right tool for hot soup makes it the right tool here. The remaining hazards are ordinary: splashing, and knuckles in the steam. A tall, narrow mug with the bell submerged solves both.

What to look for in a stick blender for this

A shaft that tolerates heat

The blending shaft is in near-boiling liquid every morning. All-Clad’s is all-metal, which our catalog notes tolerates heat and stains better than a plastic shaft; the Braun and Breville shafts are the standard detachable type and are rated for soup, which is the same temperature.

A bell that does not suction-lock

In a narrow mug, a bell that suctions to the bottom lurches when it releases — and a lurch in a mug of hot coffee is the injury. Breville’s Control Grip has a vented bell designed against exactly this, which is why it is on the list despite a one-year warranty.

A speed you can start low

Braun’s trigger responds to grip pressure, All-Clad has a variable dial, Breville has a dial and trigger under the hand. Start low, bring it up. Full speed from a standstill in a mug is how the coffee ends up on the ceiling.

Warranty, since it is a daily tool

A butter-coffee blender runs every day of the year. Braun offers three years of US warranty, All-Clad two covering labor, Breville one. The picks below are ordered that way and the full table is at blender warranties compared.

The method

1. Brew the coffee into a tall, narrow, heat-safe mug or a 16 oz measuring jug. Fill it no more than two-thirds.
2. Add the butter and oil. Let them sit ten seconds so the butter softens.
3. Put the stick blender in with the bell fully under the surface. Tilt the mug slightly.
4. Start on the lowest speed. Bring it up over five seconds. Ten to twenty seconds total is enough; the surface goes pale and foamy when the emulsion has formed.
5. Switch off before lifting the bell out. Rinse the shaft immediately under hot water.

If you are using a full-size jar: coffee in first, well below the line; butter and oil; center cap out; towel over the opening; lowest speed for ten seconds, then up briefly. Pour, and rinse the jar while it is still warm.

What you do not need

You do not need a high-power blender. The load is a cup of liquid and two tablespoons of fat, and a 280-watt stick blender emulsifies it. You do not need a “bulletproof coffee blender” sold as such; it is a stick blender by another name. And you do not need a sealed cup with a “hot” button unless the manufacturer’s manual explicitly rates it for near-boiling liquid — none of the sealed cups in our catalog does.