Place the portobello mushrooms on a baking tray, drizzle with 1 tablespoon of oil, crush and scatter over 1 clove of garlic and dot on half of the butter.
Roast in the oven for 10 minutes, or until juicy.
Heat a griddle pan over a high heat and chargrill the bread until you have deep golden grill-mark lines.
Tear the wild mushrooms, peel and crush the remaining clove of garlic, then add to a frying pan over a medium-high heat with the remaining butter.
Fry for 3 minutes, or until the mushrooms are cooked. Take off the heat and stir through the hollandaise.
Top each toast with a roasted portobello and a spoonful of the wild mushrooms. Serve with a scattering of roughly chopped tarragon and a crack of black pepper.