The Maggie Rose

We had this drink in Washington D.C. at the recommendation of my niece Maggie-- it was the best drink EVER and I have humbly tried to duplicate it as best I can. Thank you Maggie-- my quality of life is greatly improved!

2 oz. Stoli blueberry vodka
1 1/4 oz. créme de cassis (buy a fancy French one in the liquor store)
1 oz. passion fruit pureé (you can find this in the freezer section of any worthwhile grocery store or Hispanic market)
1/2 oz. lemon juice
1/2 oz. simple syrup

Shake vigorously in a cocktail shaker filled with ice and serve in the prettiest glass you have.