"Pen Pals" is the 2nd episode of Boy Girl Dog Cat Mouse Cheese which was released on January 6, 2020 on Family Channel. It aired on CBBC on November 19, 2019. It has also aired on Gulli on May 23, 2020.
Boy bakes cookies for his pen pal, Gretchen, but refuses to share them with anybody else.
The episode starts with Cat sleeping in front of the door. Cheese tries to warn her that she could get hurt if the door were to suddenly be opened. Ironically, it turns out that Cat was sleeping at a safe distance from the door, but Cheese herself gets hit when Boy opens the door on his way back from the mailbox. It turns out that he got mail from his pen pal, Gretchen, including a letter, a bracelet that says "Boy is Awesome", and cookies. Boy decides to make cookies for Gretchen, which upsets the others because he was supposed to spend the day at the movies with him.
His sisters decide to spy on him as he bakes the cookies, but he prevents them from looking in order to keep his recipe a secret. Once the cookies are done, Cheese tries one out of curiosity and convinces Girl and Cat to do the same; the cookies taste amazing, and the girls want more, but Boy is intent on sending the rest to Gretchen.
After Boy gives the package containing the cookies to the mail carrier, Cat steals them. Dog and Mouse, having seen this, try to retrieve the cookies from them, but Girl tricks Dog into eating one, and Dog's reaction piques Mouse's curiosity so he tries them as well. Both of them love the cookies. Together, the siblings eat all the cookies in the box.
Back inside the house, Girl declares that she has an idea: they steal the cookies and replace Gretchen's letters to Boy with their own letters, asking for more cookies. The plan works well at first, but then Boy gets sick of Gretchen only asking him for cookies and never actually responding to the contents of his previous letters. He had also asked her to meet him in real life, but she never responded (as her letters to Boy were destroyed by his siblings). Realizing that they won't be able to get any more cookies if Boy ends his friendship with Gretchen, Girl pressures Mouse into thinking of a plan. Mouse decides to send a letter to Boy claiming that Gretchen is allergic to light and does not ever leave her house, but will make an exception this one time and come to his house wearing a metal suit, and she would like to watch him bake his cookies. The plan is for Mouse and Cheese to wear a metal suit and impersonate Gretchen so that they can find the recipe.
Boy, having fallen for the trick, talks to "Gretchen" about a book they read together, and asks a question Cheese makes up an answer to. In the kitchen, while Boy bakes the cookies, Girl (who is watching the whole thing through a camera with Cat and Dog) tells cheese to ask Boy about his family. When Boy reveals his highly positive feelings about them, they start to feel guilty. "Gretchen" leans on the stove, causing the metal suit to melt and flail around. Boy tries to put her out with a fire extinguisher, but discovers that it was Mouse and Cheese inside the suit. Together, the others tell Boy the truth. Girl reveals that they felt upset that he kept ditching them for Gretchen, and Boy promises that he will never replace them. He wants to teach them the recipe for the cookies, but it turns out that his "irreplaceable" baking items have been destroyed, and he can never make cookies again. There is one batch left, and even though Boy suggests sharing it, everyone starts fighting over it.