The more bravely and confidently you handle this, the less awkward it will be. "Uhm, yeah, I know we've, like, been friends for a long time but, uh, I kind of, er, want, like, more. I think. Uhm." is going to be terrible even if she feels the same. "I'm having a really hard time not thinking about you and I'll hate myself forever if I don't try for more" will plant a seed even if she shoots you down.
And if she shoots you down? Don't be awkward, don't be weird, but don't for a minute pretend you're going to let things go back to what they were. People think that relationships are like glass - you have to break them to make them something else. They aren't. She might turn you down this time but if you believe in yourself and let her see it, you'll get another chance. And maybe another. And eventually she'll succumb.
I knew my wife for nine years before we started dating. Shit, I was her second husband.