Grease a one litre bowl with butter or canola spray. Pour jam into base of prepared bowl.
Using an electric mixer or food processor, beat butter and sugar until light and fluffy. Add eggs, 1 at a time, beating until just combined. Sift flour and baking powder over mixture. Add milk. Stir until well combined. Spoon mixture over jam in prepared bowl. Cover bowl with foil and secure with string.
Place pudding in a large saucepan. Carefully pour boiling water into pan until halfway up side of steamer. Cover pan. Place over medium heat. Bring to the boil. Reduce heat to low. Simmer for 1 hour 45 minutes, topping up with boiling water when necessary. Remove pan from heat. Carefully lift steamer from water. Stand for 5 minutes. Remove lid. Turn pudding onto a plate.