1. Almond Snow Gelatin: Lightly oil an 8-inch square glass baking dish with vegetable oil, wiping out any excess with a paper towel.
2. Sprinkle the gelatin over water in a large heatproof bowl to soften 1 minute.
3. Bring the milk and sugar to a boil in a 1-quart saucepan, stirring until the sugar is dissolved, then remove from the heat and whisk into gelatin mixture. Add almond extract and whisk briskly until the milk is foamy, about 5 minutes.
4. Pour into the baking dish and freeze 15 minutes (to set the foam), then chill, uncovered, in refrigerator until firm, at least 45 minutes.
5. Cherries in Port: Simmer the cherries, sugar, and Port in a 1-quart heavy saucepan, uncovered, until reduced to about 1/2 cup, about 10 minutes.
6. Set pan in a bowl of ice and cold water and chill in the refrigerator until syrupy, about 15 minutes.
7. Assemble desserts: Using a knife dipped in hot water, cut gelatin into 1-inch squares. Remove the squares from the dish with a spatula and divide, frothy sides up, among 6 chilled plates. Spoon the cherries in Port over the squares.
