Set the oven to fan 200 degrees Celsius or gas mark at 6.
Line a baking tray with baking paper to prevent sticking and runaway bits.
Place your mushrooms on a baking tray, ensure the inside points are placed upwards. Sprinkle all your ingredients (excluding the spinach for the bed) into the mushroom and place the breadcrumbs on top as the last ingredient. Make sure you split the ingredients between both mushrooms evenly.
Bake in the oven for 20 minutes. Serve on the bed of spinach.