On the kcal/£ basis, Tesco biscuits (for Americans: cookies) are more than an order of magnitude better, 487 kcal/100g, £0.22/100g, about £0.15 for as many kcal as that McMuffin: https://www.tesco.com/groceries/en-GB/products/290329100
On the basis of an actually balanced diet, boiling a pot of water and adding lentils, rice, and value frozen veg on a timer, are likewise. Which is of course why that's a staple diet in parts of the world much poorer than the UK.
On the basis of an actually balanced diet, boiling a pot of water and adding lentils, rice, and value frozen veg on a timer, are likewise. Which is of course why that's a staple diet in parts of the world much poorer than the UK.