British Steamed Jam Sponge Roll

Step 1

Fill a large pot with enough water to come halfway up the sides of a 2-litre pudding basin or heatproof bowl. Bring to a gentle simmer over medium heat and place a small upturned saucer or trivet on the bottom — this prevents the basin from sitting directly on the heat. Have the water simmering and ready before you begin the batter.

Step 2

Cut a large circle of baking parchment (about 14 inches across) and a matching circle of aluminum foil. Set them aside — you'll use these to cover the pudding during steaming.

Step 3

Place 175 g of softened unsalted butter and 175 g of caster sugar in a large mixing bowl. Using an electric mixer on medium speed, beat together for 3-4 minutes until the mixture is pale, fluffy, and noticeably lighter in color — this incorporates air, which gives the sponge its lift.

Step 4

Crack 3 large eggs into a small bowl, lightly beat them with a fork, then add them to the butter mixture a little at a time while mixing on low speed. After each addition, let the mixture come together before adding more egg — this prevents the batter from splitting and looking curdled.

Step 5

Sift 175 g of self-raising flour directly into the bowl, add 2 tablespoons of whole milk and 1 teaspoon of vanilla extract, and fold everything together gently with a spatula until just combined. Do not overmix — a few flour streaks are fine; overmixing toughens the sponge.

Step 6

Lay a sheet of baking parchment about 14 inches square on a work surface and lightly flour it. Pour the batter onto the parchment and spread it into an even rectangle about 1/4 inch thick using a spatula — the more uniform the thickness, the more evenly it will cook.

Step 7

Spread 200 g of jam evenly over the sponge, leaving a 1/2-inch border on all sides to prevent the filling from leaking out during rolling. If your jam is very thick, you can warm it gently in a small pot for 30 seconds to make it easier to spread.

Step 8

Working from one of the long edges, use the parchment to help you roll the sponge into a tight cylinder, peeling the parchment away as you roll. The jam will want to squeeze out slightly — this is normal. Once rolled, gently wrap the roly-poly in a fresh sheet of baking parchment, then wrap that in a sheet of aluminum foil to create a water-tight package.

Step 9

Grease a 2-litre pudding basin or heatproof bowl with 15 g of unsalted butter. Coil the roly-poly into the basin (it's okay if it's a tight fit; it will expand slightly as it steams), then place the parchment and foil circles on top, folding the edges down around the rim and securing them with a rubber band or twine.

Step 10

Carefully lower the basin into the simmering water — use a large spoon and a cloth or kitchen towel to help you. The water should come about halfway up the sides of the basin. Cover the pot with a lid and steam for 1 hour to 1 hour 10 minutes. The sponge is done when a skewer inserted into the center comes out clean, with no wet batter clinging to it.

Step 11

Carefully remove the basin from the pot using a cloth or oven mitts. Let it rest for 2 minutes, then remove the foil and parchment. Run a thin knife or palette knife around the inside edge of the basin to loosen the roly-poly, then turn it out onto a warm serving plate — the jam side will face up.

Step 12

Slice the warm roly-poly into 1-inch-thick slices using a sharp serrated knife dipped in hot water between cuts. Pour warm custard around or over each slice and serve immediately while the sponge is still steaming.