Preheat the oven to 180C/350F/Gas Mark 4.
Add the sweet potato and garlic cloves to a roasting tray with 1 tbsp oil, mix well and roast for 25–30 minutes until tender.
Remove the garlic and set the sweet potato aside to cool.
Season well with sea salt, black pepper and the smoked paprika.
Meanwhile, set a pan with a metal/heatproof handle on a medium heat.
Add 1 tbsp of olive oil and the spring onions for a couple of minutes.
Add the spinach, season well and cook until the spinach has wilted.
Grate in the zest of 1/2 a lemon and add the cooked sweet potato.
Whisk the eggs in a large bowl and pour this over the veggies.
Stir well and turn the heat down to low and let it cook until the edges start coming away from the pan.
Approximately 10 minutes. Preheat a broiler/grill to a medium heat.
Crumble the feta on top and place under the broiler/grill to cook the top of the frittata for 10 minutes.
Making sure the heat isn’t too high let’s the frittata cook without burning the top.
The cheese should be toasted, the top light brown and the middle set.
Cut it into wedges and either serve it straight away or let it cool and keep it in the fridge.