There are a variety of frozen desserts which are all related. The main difference between ice cream and frozen custard is the amount of eggs used to thicken the base mix.
Philadelphia style ice cream is made from a base mix of milk and/or cream, sugar, and flavorings.
French (or simply plain) ice cream is made from a base mix which is essentially a very thin custard or creme anglaise: milk and/or cream, sugar, and flavorings thickened with egg yolks or whole egg. The base mix is cooked to thicken, and then chilled prior to churning.
Frozen custard is very similar to French style ice cream, but with a greater ratio of eggs or egg yolks to dairy or liquid in the mix.
With this information, you can adapt nearly any custard recipe to be freezable as ice cream or frozen custard.
My survey of frozen custard recipes indicates a ratio of eggs to dairy of about 5 egg yolks to three cups (700 mL) dairy, or 6 whole eggs to 4 cups (1 L) of dairy.
To adapt any custard recipe for freezing, then:
Adjust the ratio of egg yolks to dairy to no more than about 5 yolks per 3 cups dairy.
You may also want to adjust the total yield to be based on no more than 3 cups dairy depending on the capacity of your ice cream maker. Many home ice cream makers have a 1 quart (close to 1 L) capacity, but you need to leave room for the air which will be incorporated as the mix is churned.
I recommend not using whole eggs for frozen custards, as the yolks facilitate a better texture, and create the rich eggy custard flavor.
Frozen desserts are served colder than custards normally are, so the flavors will be more muted. You may need to compensate by increasing the ratio of flavoring ingredients.
This will be hard to judge until you have made the frozen custard/ice cream at least once.
Cook the custard until it thickens on the stove top, per the normal custard method.
Chill it rapidly for safety, and then hold it for at least 4 hours (overnight is even better). While I cannot explain the science, empirically, allowing the mix to mature lets the flavors meld and produces a better frozen dessert.
Churn it into a frozen dessert according to the instructions of your particular ice cream maker.
Note that you can even convert a custard recipe into a Philadelphia style ice cream by eliminating the eggs completely, and simply creating a dairy/sugar/flavoring mix. These still benefit from overnight maturation before churning.
Pies originally were specifically to denote enclosed items (the crust sealed the item that was to be eaten). In many cases, the crust wasn't actually eaten -- it was a nasty charred thing that was discarded.
In time, pie crusts improved to the point at which you'd eat the whole thing ... but the star was the filling, not the crust.
Tarts, on the other hand, are closer to a shortbread cookie with some sort of a topping. The crust is typically a critical part of the item, rather than just being a container for something else. (which in part is why people mention tarts being more shallow; there's a higher proportion of crust to filling).
So, my best attempt at determining if I should call something a pie or a tart. Note that these are in order. (as I'm trying to make sure that 'pizza' is a pie, not a tat)
- fully enclosed by crust : pie
- full bottom crust, with a crumb or lattice top : pie
- no crust at all : not a tart, but not a pie, either.
- has no sugar or fat in the crust : pie
- chewy, flaky or crumb crust : pie
- not structurally sound enough to be picked up and eaten one-handed : pie
- was cooked in a tart pan : tart
- baked without a pan : galette
- over 2" / 5cm tall (not counting whipped cream or berries) : pie
- less than 6" / 15cm across : tart
- shortbread crust : tart
... I have no idea what I'd categorize thing that didn't match something already.
Best Answer
Custard should taste eggy. This is a feature, not a bug. However, from your mention of flour, I think what you're talking about is a souffle, not something like a creme brulee or along those lines. Would that be correct?
Edited based on subsequent clarifications:
Ah. Your method is sorely lacking, and your ingredients are off. You need to temper the yolks first, you need to use yolks only, and use cream instead of milk. Here is a smaller version of what I use at work for creme brulee: - 1L 35% cream - 11 egg yolks - 1C sugar - 1 vanilla bean, scraped
Bring cream to a simmer with the vanilla seeds and pod (you can use approx 1.5tsp vanilla extract, pure not artificial, instead). While it is heating, beat the yolks and sugar together until just incorporated. Pour the cream into the eggs whisking briskly to prevent curdling. Pour mixture through a fine chinois. Skim off foam, pour into ramekins. Place ramekins in a pan, add water to 1/2way up the sides. Cover pan with foil. Bake at 275 (convection) or 325 (non convection) for approx 40 minutes, until wobbly in the centre but set. Chill until set, eat.
The deflation is caused by a souffle effect coming from including the egg whites, which are never used in a custard--custards, creme anglaise, etc, are always yolks only. When you include the whites, air will be trapped inside temporarily, and will escape/collapse when the mixture cools. If you bake until fully stiff with my method, you will get hard and rubbery custard by the time it is set in the fridge.
Also, save the whites--they freeze well--for meringues or souffles.