It may be that a cake has already been made, or there is no place for making a cake, so the cake cannot be made in The Sims 4. The method of making a cake is as follows:

To make a cake, you must have a refrigerator, a cupboard, and a stove. If you invite a catering chef, he will automatically cook the food and cook the food if you have these things. Bake the cake, when the time comes you take it out of the oven and cut it and you're done.

Extended information

New ways to play in the kitchen of The Sims 4

Have some fun. Discover the amazing flavors your Sims can create with their ice cream machine, and revamp your Sims’ kitchen to add an unparalleled modern feel with sleek stainless steel appliances and new gourmet equipment. Plus, with new outfits and hairstyles, Sims will get a whole new look at eating ice cream.

1. Obtain a brand new ice cream machine. Grab an ice cream cone, gelato, or frosting, and have a variety of combinations from whipped cream and colored sugar rice to chocolate sauce and banana slices. Choose from different toppings and decorations to add to your Sims' favorites. Ice cream treats add flavor.

2 Give the kitchen a new look. From cabinets with matte glass doors to new stainless steel appliances, create the coolest kitchen so Sims can cook and relax.

3. You can see the costumes and hairstyles for eating ice cream. Your Sims are ready for some fashion, update your Sims’ appearance with a variety of new hairstyles and stylish casual clothes.

Reference: Baidu Encyclopedia: The Sims 4