Slice courgettes into 5mm slices using a mandoline slicer. Place slices in a colander; sprinkle with salt and toss to coat. Let drain for 30 minutes. Place slices on a clean drying cloth and pat dry.
Preheat the oven to 200 C / Gas 6. Line a baking tray with baking paper.
Heat oil in a pan over medium-high heat. Add onion and cook until starting to soften, 2 to 3 minutes. Add chicken (or turkey) mince and cook until lightly browned, about 5 to 6 minutes. Drain and discard any accumulated liquid.
Return pan to low heat and stir in chilli powder, paprika, cumin, garlic powder, salt, oregano and black pepper. Keep warm.
Place courgette slices on the prepared baking tray in a single layer.
Bake in the preheated oven for 5 minutes, or until crispy around the edges.
Remove courgettes from oven and top with chicken mixture and grated Cheddar cheese. Return to the hot oven and bake until cheese is melted, 2 to 3 minutes more.
Top nachos with dollops of soured cream, pico de gallo, slices of chilli pepper and spring onions. Serve immediately.