Preheat the oven to 200C (180C fan). Slice or tear the mushrooms into a 26cm nonstick ovenproof frying pan and dry-fry on a medium heat for 5 mins or until slightly charred, then remove to a plate- you may have to work in batches.
Put the kale in a bowl, drizzle over with 1/2 tbsp olive oil and add a small pinch of sea salt. Toss together, then give the leaves a scrunch with your hands.
Trim and finely slice the spring onions, then tip into a separate bowl with the cottage cheese. Finely grate in the Cheddar, season with black pepper and mix well.
Finely slice the garlic, add to the pan with 1/2 tbsp olive oil and cook for 2 minutes until golden. Add the mushrooms and season.
Lightly beat the eggs, then pour into the pan, moving the egg around with a spatula for 1 minute before allowing it to settle. Arrange the kale over the top, pushing it into the egg a little, bomb over spoons of the cheese mixture and transfer to the oven for 10 mins, or until golden and nicely set.
Slice the tomatoes and arrange on a plate. Drizzle with the extra-virgin olive oil, season to taste and top with basil leaves. Loosen the edges of the frittata with spatula, then slide onto a board. Serve in wedges with the fresh tomato salad.