In a large mixing bowl, add 2 eggs and the sugar, then whisk until the mixture is slightly foamy.
Pour in the warm milk, add the softened room‑temperature butter (do not melt it on the stove or in the microwave), the oil and salt, then mix until everything is well combined.
In a small dish, combine the yeast with a little lukewarm milk and 1 teaspoon of sugar, stir, cover and let it sit for 5–7 minutes; once it becomes foamy, pour it into the dough mixture.
Add the flour gradually, mixing and kneading until you get a soft, elastic dough that no longer sticks to your hands.
Cover the bowl and let the dough rise in a warm place for about 1 1/2 hours, or until it has doubled in size.
Once the dough has risen, divide it into 3–4 equal pieces and roll each one out with a rolling pin into a thin circle.
Cut each circle into triangles, place a small spoonful of thick jam at the wide edge of each triangle (avoid runny jam so it does not leak while baking).
Roll each piece into a crescent, starting from the wide side, then preheat the oven to 350°F (180°C).
Arrange the crescents on a baking sheet lined with parchment paper, beat the remaining egg and brush it over the tops, then bake for 15–20 minutes, or until nicely golden, adjusting the time to your oven.