1. Preheat oven to 325 degrees and have a 9-inch cake pan ready.
2. Slowly melt one cup of sugar in a small saucepan over medium heat until the sugar is completely melted and golden.
3. Quickly pour into cake pan and, using pot holders, swirl the pan around until the caramel is covering the bottom and about 1 inch up the sides (it doesn’t have to be perfect).
4. In a large bowl, combine the condensed milk, evaporated milk, eggs and vanilla. Whisk together until smooth.
5. Pour the mixture into the prepared cake pan. Place pan in a larger pan. Slowly add hot water to the larger pan so the water comes up 1 inch on the side of the cake pan.
6. Bake for 35 to 40 minutes or until the custard is set, which is when a knife comes out clean.
7. Cool completely and then refrigerate for at least 6 hours or overnight.
8. When it comes time to serve, run a knife along the edge of the pan to release the flan. Place a serving plate over the top and flip the flan over very carefully and let the syrup run over the top of the flan. Serve in slices with raspberries or just on its own.