It is actually virtually impossible to cook all the alcohol out of food - below is an excerpt from a study comparing various cooking methods:
A study conducted by the US Department of Agriculture’s Nutrient Data Laboratory calculated the percentage of alcohol remaining in a dish based on various cooking methods. The results are as follows:
Preparation Method Percent of Alcohol Retained
alcohol added to boiling liquid & removed from heat 85%
alcohol flamed 75%
no heat, stored overnight 70%
baked, 25 minutes, alcohol not stirred into mixture 45%
baked/simmered, alcohol stirred into mixture:
15 minutes - 40%
30 minutes - 35%
1 hour - 25%
1.5 hours - 20%
2 hours - 10%
2.5 hours - 5%