Whisk together the flour and poppy seeds in a medium bowl. Set aside.
In a large mixing bowl, beat the eggs, sugar, and salt until combined. Stir in 1 cup of warm milk and vanilla extract. Continue to mix for 1 minute.
Add the flour mixture and mix until nice and smooth, scraping down the sides of the bowl. Pour in the remaining milk while the mixer is running on low. Stir in the vegetable oil and baking powder. Mix until the batter is smooth, about a minute. Let the batter rest for 10-15 minutes at room temperature.
Heat a non-stick frying pan over high heat. (I use a 10-inch non-stick skillet, the bottom of my 10-inch pan measures 7 inches, which means the crepes will be 7-inches round.) Reduce the heat to medium-high.
Pour a scant ¼ cup of batter into the hot pan and tilt the pan around, so the batter is evenly distributed.
When the edges of the crepe start to brown slightly, run the spatula around the edges. Then insert the spatula under the crepe and flip it over. Cook until nice and brown, about 30 seconds. Transfer onto a plate and continue with the rest of the batter. It takes about 1 minute per crepe, when the pan is nice and hot. Cool the crepes completely before filling. If making ahead, cover with plastic wrap and refrigerate until ready to use.