Place a large pot of salted water to boil for the pasta. Meanwhile, mash most of the strawberries in a bowl, and slice a few for a final garnish. Over a low flame, melt the butter and olive oil together. When melted, add the strawberries and the vodka. Stir for about a minute and then add the cream, salt and pepper. Cook for about 5 minutes. When the spaghetti is almost al dente, drain it, and mix into the strawberry mixture. After about a minute, add the Parmigiano. Serve immediately with a garnish of the remaining strawberries and a sprinkle of Parmigiano.