Preheat the oven to 180°C, or 160°C for a fan-assisted oven. For a gas oven, use gas mark 4. Line a 10 × 20 cm loaf tin with baking paper to prevent the bread from sticking and to make removal easier.
Remove any remaining skin and seeds from the pumpkin. Grate the prepared flesh with a box grater or process it with the grating attachment of a food processor. Place the grated pumpkin in a large mixing bowl.
Crack the room-temperature eggs into the bowl containing the grated pumpkin, then pour in the olive oil. Coconut oil or vegetable oil may be used in the same quantity. Stir thoroughly until the pumpkin is evenly coated and the wet ingredients are well distributed.
In a separate bowl, stir the baking powder into the plain flour. Sift this dry mixture over the combined pumpkin, egg, and oil mixture. Fold gently until no visible pockets of dry flour remain. Stop mixing as soon as the batter is combined to avoid developing an overly dense texture.
Transfer the batter to the lined loaf tin and spread it evenly, smoothing the surface with a spoon or spatula. Scatter pumpkin seeds across the top when using the optional garnish.
Place the tin in the preheated oven and bake for approximately 1 to 1½ hours. Begin checking after 1 hour by inserting a clean knife into the center of the loaf. The bread is ready when the knife comes out clean.
Remove the baked loaf from the oven and leave it undisturbed in the tin for 1 hour. Carefully lift it from the tin, place it on a wire cooling rack, and allow it to cool completely before cutting into slices.