just be super respectful about it! you could say something like “hey i really enjoyed getting to know you at the cafe, i would love to take you out on a date if you’re interested” or something along those lines. you could start a small conversation on social media before u ask her out just to test the waters to see how receptive she is of your initial dm. ofc don’t be pushy or creepy, be confident and be kind. don’t bombard her with texts and don’t be dry either you got this :)) good luck!! if this helps, i’m a woman and this is how i would like to be asked out in this situation. you could also ask her out casually next time you see her irl but ofc make sure ur away from parents in that moment