In a large bowl whisk together flour, baking powder, sugar, and salt.
In another bowl whisk together eggs, butter (the more butter you use the crunchier they'll be, I find that 8 tbsp is perfect), and milk.
Warm melted butter may separate into flaky clumps when mixed with milk. I just stick it in the microwave for 1 minute then stir and the lumps will go away.
Make a well in the center of the dry ingredients and pour in the egg/milk mixture.
Gently whisk together just until combined.
Baking time and amount of batter will depend on your individual waffle maker. I use about a cup of batter for 2 waffles and mine take about 3 1/2 minutes to bake. I like to bake mine until they are a dark golden brown. Cooking spray usually isn't needed if you use 8 tbsp or more butter in the batter.