Making dulce de leche using sous vide is about as mindlessly simple a process as you can hope.  You can cook the sweetened condensed milk in the can if you’d like—many do—but I pour the can into a jar I have sized just for this (and that same jar then stores it in the refrigerator).

Other folks cook theirs for 12 hours but I push mine to 15 hours for a more golden flavor.  Set the cooker to 185f and drop in your can or jar.

This got me to thinking:  “Can I make browned butter the same way?”

Today I am trying a cube of butter as 185f for 12 hours and we’ll see what that does.  On-line I saw many folks claiming you can’t do it because the water will prevent the browning.  I am rightly dubious about this claim.  Sweetened condensed milk is about 27% water while butter is only about 16-18% water.  If I can caramelize the sugars in sweetened condensed milk with nearly twice the water, I ought to be able to do similar in butter.

The butter solids, water, and butter fat do separate out from one another.  After maybe an hour you have perfect seperation.  You can use this separated butter to make a not-quite-perfect version of clarified butter by handing the bag in the refridgerator until the fat solidifies and then cutting the corner to drain the water and milk solids.

If you leave the separated butter at temperature for a day or so you will acheive some browning of the butter solids, certainly enough to give a carmelized arome and flavor to those solids.  Generally, however, I find this method particularly inefficient and will probably neither use it to make clarified butter nor to extract browned butter solids.