Is it heavy cream, light cream, or coffee creamer? Each has differences and limitations. Coffee creamers may or may not even contain dairy along with all sorts additives and should only be added to drinks such as coffee, hot tea, or to flavor smoothies.
Light cream powder is lower in milk fats, more easily damaged by heat and acids when used in cooking and prone to curdling (okay making for quicker, lower heat soups and sauces), it cannot be used for whipping cream as it will not go beyond soft peak stage and the soft peak stage will not hold up long enough to use as a whipped cream even as a eat-it-now topping. Because of this curdling when exposed to acids, it can sometimes be used to make a very soft butter spread or cottage cheese or paneer BUT there are so few curdles that it is neither efficient nor frugal.
Heavy cream, especially if full fat, (fat content levels vary) is perfect for making creamed soups and sauces. It be used to make Alfredo sauce, can be used to make Half-n-Half, etc.
Not quickly, but higher fat or full fat heavy cream powders can also be whipped (whipping cream) stiff peak stage (just quite as stiff as with actual whipping cream) which will remain stable just long enough for eat/use now whipped topping purposes. Again, depends upon fat content as to how well it will actually work and how long it takes to achieve stiff peak stage, plus, it cannot be achieved by hand -- need high powered food processor, a blender such as a Vita-Mix or Ninja bullet blender, or a stick blender and can take about 20 minutes of blending on average -- again, depending upon the fat content -- the more fat the less time consuming, the less fat the more time consuming. Much harder to curdle than lower fat cream powder (again, NOT coffee creamer) but it is actually possible if the fat content is higher and if use enough acid (i.e. 5 percent acidity bottled lemon juice or vinegar) and helps if also add whole milk or whole milk powder to boost the fat content (or can boost it with a high fat butter). Fats can go rancid, however, and dairy powders once opened only last about one week in the frig so are best kept stored in the freezer.
To answer your question: 2 Tbsp to 3 Tbsp powder to 1 Tbsp water = liquid heavy cream. For a thick creamy Alfredo sauce, you are looking at about 2 cups heavy cream powder, PLUS 1/2 cup whole milk powder, PLUS 2 cups cheese powder and 4 cups of water along with your seasonings and herbs.Combine 1 Tbsp any milk powder with 1 Tbsp heavy cream powder and 2 Tbsp water to make liquid Half-n-Half. Once mixed and reconstituted, these milks, creams, and even butter need to be kept refrigerated and consumed or used within 4 to 7 days.
