Clean the summer truffles under running water, peel deep furrows with a small knife. Finely chop the truffles.
Roast the pine nuts in a non-fat frying pan until they are brown, then let cool and grate finely in a mortar. Finely grate the parmesan, mix the truffles with the pine nuts and stir in the parmesan. Slowly pour in the truffle oil and olive oil and stir in. Season the truffle pesto with salt and balsamic vinegar.
Froth the butter in a small pan and toss the chopped thyme leaves in it. Stir the thyme butter into the truffle pesto.