In a large bowl, whisk together the eggs and sugar until the mixture becomes frothy.
Next, whisk in the butter, milk, and vanilla. Gradually add the flour and salt to the mixture, whisking until the batter turns smooth. The consistency of the batter should be thin, but if needed, you can stir in additional milk.
Heat an ice cream cone machine, a waffle griddle, or a thin crêpe pan over medium heat, and lightly brush it with oil. Pour approximately ¼ cup of batter onto the skillet and spread it into a thin circle by turning it.
If using a waffle machine, follow the machine's instructions. If using a griddle or a pan, do not close the lid. Instead, wait for the underside to become golden brown, flip the waffle, and cook until the other side turns golden. Remove from the pan and shape it into a cone while it's still hot, ensuring to seal the end.
Place the formed waffle cones on a wire rack to cool and harden completely, usually taking 3 to 4 hours. Repeat the process with the remaining batter.
When the cones have hardened, proceed with making the chocolate-sprinkle edge. Add one cup of the chocolate to a microwave-safe bowl. Microwave for 30 seconds, stir, and then microwave again for another 30 seconds. Repeat the process until all the chocolate is melted.
Hold an ice cream cone upside down and dip it straight down into the bowl of melted chocolate. Very gently shake the cone in an up-and-down fashion. This will force the excess chocolate to drip off and back into the bowl of melted chocolate.
Next, pour the sprinkles into a flat plate. Roll the chocolate-covered ends of the cone in the sprinkles until all the chocolate is covered. Set the prepared cone inside a glass. Repeat with the remaining cones, setting each one into its glass. Wait for the chocolate to harden for at least 2 hours.