Heat a large skillet over medium heat. Add hazelnuts and toast until browned, stirring often. Place the nuts in a dish towel and rub together to remove the skins. Set aside.
Place the sesame seeds in the hot skillet and toast until golden, stirring often. Set aside.
Place the coriander, cumin, fennel, and thyme in the hot skillet. Toast until fragrant and beginning to darken. Remove from heat.
Put the toasted hazelnuts in a spice grinder or mortar and pestle and grind until coarse. Remove to a medium bowl. Add the toasted spices to the spice grinder or mortar and pestle and grind until coarse. Stir into the hazelnuts. Mix in the toasted sesame seeds. Season with salt and pepper.
Serve with olive oil and flatbread. Store the extra in the refrigerator.