Step 1: Prepare the Steaming Setup
Fill a large pot with a couple of inches of water, making sure the water won’t touch the pudding when placed inside. Bring it to a simmer.
Grease a 1.5-2 quart pudding basin or a heatproof bowl, and set aside.

Step 2: Mix the Ingredients
In a medium bowl, whisk together the flour, baking soda, cinnamon, nutmeg, ginger, and salt.
In another bowl, combine the grated carrots, brown sugar, egg, melted butter, milk, vanilla extract, and lemon juice (if using).
Add the wet ingredients to the dry ingredients and mix until combined.

Step 3: Steam the Pudding
Pour the batter into the prepared pudding basin, smoothing the top.
Cover the top of the pudding basin with a piece of parchment paper or foil, securing it with kitchen twine or a rubber band.
Place the pudding basin in the simmering water (in the pot) and cover the pot with a lid. Steam for about 1 to 1.5 hours, checking occasionally to ensure the water is still simmering.
To check doneness, insert a toothpick into the center of the pudding; it should come out clean when fully cooked.

Step 4: Serve the Pudding
Once the pudding is done, carefully remove it from the pot. Let it cool for a few minutes before unmolding it onto a serving plate.
For the optional sauce, whip the heavy cream with powdered sugar and vanilla extract until soft peaks form. Serve the pudding with a dollop of cream sauce on top.