Stick With Brown Butter When Making Key Lime Pie

Key lime pie is not subtle on the flavor front, and nor should it be. The refreshing burst of lime balanced with the salty, buttery richness of the crust is like summertime in the Florida Keys on a plate. That crust, whether it's shortcrust or graham cracker, is an integral part of the whole experience. It needs to be bold. Otherwise, it will get lost in the tartness of the lime. This is where utilizing brown butter can come in handy. 

Brown butter is butter that has had its flavors amplified through the process of browning. As the butter melts, the milk solids within separate, darken, and sink to the bottom of the pan, turning the melted butter into a rich brown sauce. Beurre noisette, as the French call it, can be used in a variety of savory and sweet dishes. 

With key lime pie, adding brown butter to the crust brings a fragrant, nutty flavor that amplifies the flavor of the entire pie. Whether you're making shortcrust or graham cracker crust will determine exactly how you incorporate the brown butter into the pie. It's a great way to optimize flavor, and it couldn't be simpler to make. 

Making brown butter may be easy, but it requires constant attention. Add your desired amount of unsalted butter to a cold stainless steel pan and melt over medium-high heat. Unsalted butter will foam less than salted, making it easier for you to keep track of the milk solids. As the butter simmers and cooks off its water content, foam will begin to appear. As the foam dissipates, you should see the whitish milk solids — the proteins that give brown butter its signature nutty flavor — begin to separate from the butter fat. These will sink to the bottom of the pan and begin to brown. 

Continue to stir the butter in the pan with a spatula to ensure the milk solids don't stick and burn. Once the butter turns a hazelnut brown hue, remove it from the heat and immediately place it into a bowl. If you keep it on the heat any longer, the butter will burn.

To incorporate brown butter into your key lime pie crust, you need to determine the kind of crust you are making. If you're making shortcrust, the butter must be cooled and re-solidified to work it into the dough. If you're making graham cracker crust, slightly cool the butter before mixing it in. Melted butter acts as the binding agent for graham cracker crust. No matter how you use brown butter, it's a great sauce that does wonders for key lime pie.