In a medium size sauce pan, combine milk and cream.  Bring to a low simmer.  In a large mixing bowl beat egg yolks.  Slowly add in sugar.  Beat until mixture is light yellow and thick.  Slowly pour hot milk mixture into the egg yolk mixture beating constantly.  Return to pan; add salt and cook over low heat until the mixture coats the back of a spoons. Remove from heat.  Add vanilla and root beer extract.  Pour into a large bowl, cover with plastic wrap and refrigerate until completely cool.  2-4 hours.  I prefer overnight.  Makes 1 1/2 quarts.

Pour chilled mixture into an ice cream maker.  Freeze according to manufacturers directions.  Pour into a container and return to freezer.  Freeze until firm.

For root beer floats:  Scoop ice cream into tall glasses.  Pour chilled root beer over ice cream.  Serve immediately.