Combine evaporated milk with sugar in a heavy, large stockpot and place over medium heat. Stir constantly and bring to a boil. Cook the syrup, stirring often, until a candy thermometer reads 235 degrees F (110 degrees C) or a small spoonful of syrup dropped into a glass of cold water forms a soft ball, 5 to 8 minutes.
Stir pecans and butter into the syrup and continue to cook until solid crystals of candy begin to form on the side of the pot, about 30 minutes. Remove from heat and stir vanilla and almond extracts into candy.
Pour candy into prepared dish and let cool for 10 minutes before cutting into squares.