The best option to edit the issues with verb voice and mood is:
"An hour after Sheila placed the lasagna in the oven, we smelled a tantalizing aroma and our stomachs began to growl. 'Take it out of the oven, and then you should cut everybody a slice,' Cynthia said to Sheila."
This choice uses active voice effectively by stating "we smelled" instead of "a tantalizing aroma was smelled," which makes the sentence clearer and more direct. It also retains the conversational tone in Cynthia's dialogue.