Sweet potato, avocado & feta muffins

Name: Sweet potato, avocado & feta muffins
Prep time: 20 min
Cook time: 20 min
Total time: 40 min
Cuisine: British
Ingredients: 1 sweet potato (about 200g), peeled and chopped into small chunks; drizzle of flavourless oil such as vegetable or sunflower; 1 large avocado peel and stone removed, roughly chopped (about 150g prepared weight); 100g ground almonds; 100g fine polenta; 80ml maple syrup; 3 large eggs; 1 ½ tsp baking powder; 1 tsp bicarbonate of soda; 100ml semi-skimmed milk; 50g feta crumbled, optional; 2 tbsp mixed seeds; ¼ tsp sweet paprika