Shell & crush 5 walnuts, reserve the 6th. Rinse the basil & chop half. Lightly rinse, dry, & dice mushrooms. Saute in a tablespoon of butter for 10 mins over high heat.

Preheat the oven to 350° & butter the 4 ramekins. In a large bowl, beat the eggs with the half-and-half, sour cream, five-spice powder, salt & pepper. Add the mushrooms, peeled & crushed garlic, crushed walnuts & the chopped basil. Pour into the ramekins. Bake for 20 mins.

In a food processor, blend a few basil leaves with lemon juice & place in a pan over low heat. Whisk the remaining butter in gradually until incorporated. Season with salt & pepper.

Invert the flans into plates surrounded by basil butter, and garnished with the remaining basil leaves & 1/4 walnut.