Cow in a Jar
Automatically fills with milk over time.
The Cow in a Jar is a genius invention based on the Milk Jar.
Inside is a tiny cow that will continuously produce milk over time.
Check the Cooking Table for more information on multi-block Kitchens.
Crafting (in-world)

I also made a short instructional video visualizing the process:
Drop an anvil block on a cow above a milk jar.
Usage
- Right-click with a bucket of milk to put milk into the milk jar.
- Right-click with an empty bucket to take it back out.
Configuration
cowJarMilkPerTick
Integer
The amount of milk the cow in a jar generates per tick. (Default: 1)
compressedCowJarMilkMultiplier
Double
Ex Compressum compatibility. Multiplier applied to the milk per tick for Compressed Cow in a Jar. (Default: 9.0)
cowJarEnabled
Boolean
If true, a cow can be squished into a Milk Jar by dropping an anvil on top. (Default: true)