What is the best way to tell a female friend that I like her?

We have been friends for 10 months
She is shy but brave to fight it
I am shy but I am starting to come out of my shell
We talk about love and relations and send each other cat memes and we read books about relationships together

I have no idea if she likes me (we both suck at flirting)

What is the best way to tell her I like her and at the same time preserve the friendship

I think in person is the ideal case
What is the best way to tell a female friend that I like her?
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