I don't own Doctor Who
In the TARDIS med-bay the Doctor had some machine over Sofia's arm, fixing it.
"Happy Birthday" the Doctor comments.
"Thank you" Sofia also comments
"Here" the Doctor hands Sofia a key on a chain, "It's a TARDIS key, I should have given on to you a long time ago."
"Thanks" Sophie grins.
Something beeps.
"That's saying 'your arm is fully healed.'" The Doctor says.
The Doctor leads Sofia into the kitchen, in the kitchen there is a small chocolate cake with sixteen candles on it.
"Happy Birthday" the Doctor says again, "I asked the TARDIS if she would make you a cake, surprisingly, she agreed. The TARDIS really seems to like you."
"Thank you, both of you." Sofia pats the wall affectionately.
The lights flutter briefly, as if as a 'you're welcome'.
"Now I believe," the Doctor says, "The human tradition is to blow out the candles and make a wish."
Sofia grins, and does just that.
This is the part where the studio audience goes "AWWW"