Larger muffins: prefer a bigger muffin? Divide the mixture between 6 muffin cases instead of 8. They’ll be slightly larger with a more generous jammy centre. Bake at the same temperature and start checking at around 15 minutes, adding a couple of extra minutes if needed until just cooked through.

Protein powder: Different protein powders absorb different amounts of liquid, so the exact consistency of the batter can vary. It should be thick and spoonable rather than dry or stiff.

Troubleshooting

• My batter looks really thick: Different protein powders and oat flours absorb different amounts of liquid. Add milk 1 teaspoon at a time until the batter is thick but easily spoonable.

• The jam leaked out: A little jam escaping is completely normal as they're only small muffins. Make sure there's enough batter underneath and keep the jam in the centre and away from the edges, then completely cover it with the remaining batter.

• My muffins are dense or rubbery: The batter may have been overmixed. Fold only until the dry ingredients have disappeared, then stop.

• My muffins seem dry: They may have been baked for slightly too long, or your protein powder may be particularly absorbent. Start checking at 13 minutes and remove them as soon as they're just cooked through.

• My muffins didn't rise much: Make sure your self raising flour and baking powder are fresh, and don't leave the mixed batter sitting around for too long before baking.

• The tops aren't very sugary: That's intentional this recipe uses a light doughnut style coating. Increase the topping slightly if you prefer a more noticeable sugary finish.

• If you don't want to use protein powder: Leave out the protein powder and replace the 15g vanilla protein powder with 15g additional self raising flour. Because protein powder generally absorbs more liquid than flour, start with 60ml milk instead of 70ml, then add the remaining milk only if needed to get a thick but spoonable batter. You may also want to add a little extra vanilla extract if your protein powder normally adds quite a lot of vanilla flavour.