Asking a confident girl out?

okay heres my problem im fine with asking a girl out but there is this new girl i know & i know without a doubt thats she likes me ,,,now for some reason i find it harder to ask a girl out that i know likes me other then not knowin if she does ,,plus shes like the most confident person i know so that makes it it bit harder ,,any tips on anything i guess ,,anything would help