Combine oil and anchovies in a skillet over medium-low heat; cook, stirring, until anchovies begin to melt into the oil, about 1 minute.
Add garlic and red pepper flakes; cook until garlic softens, about 3 minutes; add cauliflower florets and 1/2 cup water; cover, cook on medium-low until the florets are soft enough to be pierced with a knife, but not so soft that they can be crushed, about 7 minutes.
Uncover; raise heat to high, cook, stirring, until water evaporates, leaving a thin layer of syrup in the bottom of the pan, about 5 minutes.