Sous vide sweet potato casserole with pecan streusel and whiskey marshmallow

Subdivide the sweet potato cubes into two bags, maybe with a cinnamon stick or two, and cook in a 170F water bath one and a half hours, weighed down to stay submerged.

Brown the unsalted butter in a medium saucepan over medium heat, swirling constantly until the milk solids separate and turn nutty brown, then cool.

Combine the cooked potatoes in a large bowl with the brown butter and its brown bits, light brown sugar, creme fraiche, maple syrup, vanilla, cinnamon, nutmeg, salt and the beaten egg yolks.

Mix with a paddle until evenly distributed, then puree in a food processor in batches about 60 seconds until dreamily smooth.

Spread evenly in a nine by 13 casserole generously lubed with unsalted butter.

Combine the flour, brown sugar and roughly processed pecans, then add the melted butter until the streusel has the texture of very wet sand.

Press it together, crumble over the sweet potatoes and bake at 325F for 25 to 30 minutes.

Dissolve the gelatin in the cold water and set aside to set.

Bring the sugar, water, corn syrup and whiskey to a simmer covered in a small saucepan, then uncover and cook to 255F, the firm ball stage.

Kill the heat, add a splash of whiskey and cool to 212F; melt the gelatin over a double boiler.

Combine the gelatin and the syrup in a stand mixer and whip on medium high, starting slow, 10 to 15 minutes until nearly quadrupled and at stiff peaks.

Pipe the marshmallow onto the slightly cooled casserole, or pour it into a casserole and cut into cubes for plain marshmallows.

Let set an hour and brown in a 350F oven, or torch it if the casserole is still hot.