With just a few minutes of heating, raw almonds lose their chewy texture and mild flavor, gaining both crunch and a deep, nutty taste. Like all shelled, raw nuts, almonds can go rancid at room temperature. If you don't plan to toast them within a few months, keep raw almonds in the refrigerator for up to one year or in the freezer for over a year.
The longer you toast almonds, either sliced, whole or slivered, the more intense their almond flavor becomes. Spread the nuts on a cookie sheet or baking pan in a single layer, and roast them at 350 degrees Fahrenheit for 7 to 9 minutes, no stirring required. Sliced or slivered almonds turn golden brown; the skins on whole almonds turn a darker brown, but the change is harder to recognize. Keep your eye on sliced and slivered nuts after 7 minutes to help ensure that they don't become too browned. You'll also know the almonds are done when you can smell their aroma as you open the oven door.
You don't need to heat up the oven if you are toasting only a small amount of almonds. Instead, you can roast them in a pan on the stovetop -- but keep a close watch on the nuts so they don't burn. Set the pan on medium heat and shake it every 10 to 15 seconds for 1 to 2 minutes for sliced, slivered or chopped nuts. Whole almonds take about 4 to 5 minutes to become thoroughly toasted and crunchy.
Alice Henneman, an Extension Educator with the University of Nebraska-Lincoln Extension, recommends experimenting with the microwave for toasting up to 1 cup of almonds. The method begins with tossing almonds in 1/2 teaspoon of oil or melted butter for each 1/2 cup of nuts, spreading the nuts in a single layer on a microwave-safe plate and microwaving them on high for 1 minute. Then, stir the almonds and microwave for one more minute. Sliced and slivered almonds take 2 minutes, while whole almonds take an additional minute or two.
Blanched Versus Raw Almonds
Blanched almonds -- those you've dropped into boiling water for 1 minute then popped out of their peels once they've cooled -- cook in the same time as whole almonds still with the peel. With blanched almonds you'll find it easier to determine that the nuts are completely toasted because they will turn the same golden color that sliced and slivered almonds do. Blanched almonds taste delicious when you toss them in butter or olive oil before toasting them using your preferred method.