Preheat the oven to 200C/400F.
In a large baking sheet mix both types of mushrooms with shallots, salt, pepper, rosemary, garlic, butter and oil. Bake for 40 minutes, mixing 2-3 times throughout cooking.
4-5 shallots, 3 garlic cloves, 1 rosemary sprig, 200 g 7 oz cremini mushrooms, 200 g 7 oz oyster mushrooms, separated into smaller pieces, 2 tablespoon butter, a pinch of salt, 3 tablespoon olive oil
In a large bowl whisk flour with salt and baking powder, make a small well in the center and pour eggs and ½ of the milk in. Whisk until well combined, pour another ½ of the milk and whisk once more until fully combined.
225 g 8 oz all-purpose flour, ¼ teaspoon baking powder, 4 eggs, a pinch of salt, 300 ml 1 ¼ cup milk
Pour 3-4 tablespoon of canola or vegetable oil into a baking pan (32x22 cm) and preheat in the oven for 5 minutes.
Pour batter into preheated oil and top with mushroom and onion mix.
Bake for 25-30 minutes more.