Vegan Cottage Pie with Sweet Potato

Ingredients 

1 medium onion, finely chopped

 2 medium carrot, peeled, finely chopped

A tin of Lentils

 2 teaspoons Vegan Worcestershire sauce

 2 tablespoons tomato paste

 400g can crushed tomatoes

 1 teaspoon dried mixed herbs

 2/3 cup frozen peas

 400g  sweet potato, peeled, and chopped, and 200g white potato

 1/4 cup Oat milk

 20g Flora butter