Start with genuinely soft butter and line the loaf tin before any ingredients enter the bowl. Butter that yields when pressed but is not oily will combine quickly; fridge-cold cubes leave yellow lumps and can turn a simple all-in-one cake into an exhausting mixing job.
Set up citrus work in the right order: wash and dry the lemons, zest one while it is still whole, then cut and squeeze. Show the child how to move the lemon across the zester rather than rubbing fingers towards the teeth, and rotate as soon as the white pith appears.
Crack each egg into a small cup first. A shell rescue is much easier there than in a bowl full of flour and butter. Mix on a low speed to begin so flour stays in the bowl, then stop once the batter is pale, smooth and drops reluctantly from the spoon.
Level the batter but do not chase a perfectly flat top; a central crack is normal for a loaf cake. Keep the oven closed during the early rise. Near 45 minutes, an adult can check the centre: wet batter needs longer, while a clean skewer or a few dry crumbs means it is ready.
Mix the drizzle while the cake bakes and expect it to look grainy. Put the hot tin on a stable heatproof surface, prick the loaf, and spoon slowly from end to end. If drizzle pools at the sides, pause for a few seconds and let the first spoonfuls soak in before adding more.
Cooling is part of the recipe. The warm cake is fragile and the syrup needs time to settle, so leave it in the lined tin until completely cool. If the centre dips slightly, serve it proudly; if it is still wet rather than just sunken, it was underbaked and should not be eaten as finished cake.