Go to the BP_ExtCookingMenu and create a new function called Pause/UnPauseSingleSlot with 2 inputs the first call Index and set its type to Integer and the second call Pause and set to a Boolean. Then copy the image below, note you may need to untick content sensitive in the right mouse menu to get the Cooking Slot Index variable.

Next go to the BP_PlayerInventory event graph and create a new custom event called ClientPause/UnPauseCookingSlot set it to Run On Owning Client and tick on Reliable. Then add two inputs first called Index and set to an Integer and the Second called Pause set it to Boolean. Then copy the image below.

Next go to the BP_CookingComponent and create a new function called Pause/UnPauseSingleSlot and add two inputs the first called Index set to an Integer and the seconds called Pause set to a Boolean. Then copy the image below.

Next go to the Update Cooking Times function and create a new local variable called IndexL and set its type to Integer.

Then create another local variable called RecipeL and set it to S_CookingRecipe.

Next create a new variable (Not local) and set it to an Integer and call it PausedIndexs then set it to Integer and set its replication to Replicated. Then set it to an array by clicking the button next to the variable type drop down.

Below are more zoomed in images of the same function, make sure you follow them carefully.

Next go to the Update Cooking Items function and add the nodes shown in the image below.

Next go to the BP_ExtCookingMenu and add the following nodes in the Construct Cooking Slots function.