"Never mind that, do you think he remembers what You-Know-Who looks like?"
Their mother suddenly became very stern. "I forbid you to ask him, Fred. No, don't you dare. As though he needs reminding of that on his first day at school."
"All right, keep your hair on." (Harry Potter and the Sorcerer's Stone)
Don’t you dare is an idiom showed in OALD and dare can be stranded, says CGEL (p.110). But when you say a directive not to do something like don’t you dare ask him about it, the complement of dare needs only to be an bare infinitive, not permitting don’t you dare to ask him about it? (OALD says lexical verb dare can have to-infinitive or bare infinitive.)