Quick and easy quest. Head to the castle in Lumbridge and speak to the cook in the kitchen.
He'll ask you to get an egg, a bucket of milk, and a pot of flour. All of which are easy to find near the castle.
You can grab a pot from the table in the kitchen if you need one for the flower. Head north up the road and you'll find lots of chickens to get an egg from. There are also farms with cows in - find a Dairy Cow and use the bucket on one. You can use the flower mill just outside of Lumbridge to fill your pot.
Once you have all three - head back to the cook to finish the quest.