Preheat oven to 400° F / 205° C. Line a half-sheet rimmed tray with a silicone baking mat and set aside until ready to use.

Unroll puff pastry on a silicone rolling mat or lightly floured countertop. Use a rolling pin to make the pastry a few inches wider, or a sharp knife to trim away any excess, until you have a rectangle that is about 9 1/2 x 11 inches in size. Position the rectangle with the longer side facing you.

Measure the Marmite into a microwave-safe bowl. Microwave on medium-high for 15 seconds, or until slightly runny and bubbly on top. Stir.

With a flexible rubber spatula or small palette knife, spread the Marmite over the pastry, covering the entire surface in a very thin layer.

Sprinkle the grated cheese over top of the Marmite, distributing it evenly over the entire surface.

Fold the rectangle in half, bringing the longer back edge forward to meet the edge closest to you. You will now have a 4 3/4 x 11-inch rectangle. With your fingertips, gently pat down the pastry.

With a sharp knife, slice the rectangle vertically into 3/4-inch strips. You should have 15 total.

With your hands, twist each individual strip into a tight spiral.

Arrange twists on prepared tray.

With a 1-inch pastry brush, brush pastry (flat, white parts only) with beaten egg.

Bake in preheated oven for 22-25 minutes or until bubbly and golden brown, with bits of crunchy Marmite oozing onto the tray.

Transfer to a wire rack. If desired, break off any crunchy bits of Marmite.

Serve warm or at room temperature. Store leftover puff pastry cheese twists in an airtight container at room temperature for up to 2 days.