1For raw/unroasted garam masala-
Coarsely grind all spices until roughly the texture of coffee grounds. Traditionally a mortar & pestle or "sil batta" was used to get this texture. Garam masala is not supposed to be like that finely ground powdery stuff you see sold at stores. To get the traditional 'coffee grounds' texture we're looking for use the 'pulse' button on your mixie, food processor, or coffee grinder until you get the desired results. If you are using a coffee grinder or small mixie jar you might want to grind each spice separately in batches to get a consistent texture. Breaking the cassia bark (or cinnamon sticks) into smaller pieces before grinding helps also. Store in an airtight container out of sunlight.
2Fast & easy dry roasting oven method-
1) Preheat oven to 220F/100C.
2) Spread all spices (except mace, nutmeg or allspice) over 13 inch by 9 inch baking pan or cookie sheet. Bake spices for 10 minutes.
3) Allow to cool completely & grind coarsely (including mace, nutmeg, or allspice) using pulse button in mixie, food processor, or coffee grinder. Store in an airtight container out of sunlight.