Fresh Cream 

Fresh cream can only come from a cow. If you have access to fresh cows milk, that being milk that has is not homogenized, pasteurized or separated, leaving it for about a day it will naturally separate by gravity. The cream rises to the top allowing the heavy cream to be skimmed from the top of the raw milk.

Even in the most well stocked bar cows are rare to find. Using heavy cream or half and half (1/2 cream 1/2 milk) usually found in a dairy aisle of a local grocer are acceptable substitutes for fresh cream in a Brandy Alexander.

If you live in Canada cream is not a dairy aisle staple. Check an organic market for 'whipping cream' that is not ultra pasteurized (UHT).  In the UK look for 'whipping cream' or 'double cream'.  Where possible the amount of butterfat in the ingredient you choose should be at least 36% butterfat.

For a richer drink substitute fresh vanilla bean ice cream for heavy cream in a Brandy Alexander.

Brandy Alexander with Ice Cream

From cooks.com 

FROZEN BRANDY ALEXANDER  

6 lg. scoops vanilla ice cream
or 3/4 filled blender
3 oz. brandy
3 oz. cream de coco (brown)

Mixing instructions:

Mix all ingredients with ice in a shaker or blender.
Strain into a chilled cocktail glass.

The Brandy Alexander drink, like many cream or Half & Half-based drinks, can also be made frozen: blend the ingredients with 2 scoops of ice-cream instead of the cream or Half & Half, and a scoop of crushed ice, and serve in a tall wine glass.

Originally made with gin instead of brandy and called an Alexander, other variations are the Alexander's Sister (with Bols Peppermint and gin). Many find cream too rich, and use Half & Half, which is a mix of half milk and half cream

This is the recipe from BOLS brand: 

1 oz cognac
1 oz dark (brown creme de cacoa)
2-3 scoops vanilla ice cream