Special equipment: a spice grinder
For the niter kibbeh (spiced butter): Melt the butter in a small saucepan over medium-low heat, swirling occasionally. Stir in the ginger, allspice, fenugreek, oregano, turmeric, cardamom, garlic and onions and bring to a simmer. Simmer until the butter is clear and the milk solids remain on the bottom of the pan, about 30 minutes. Reduce the heat to low if the butter is boiling too quickly--if it burns it will taste bitter.
For the berbere (spice mix): Whisk together the chile powder, paprika, cayenne, ginger, salt, garlic powder, onion powder and nutmeg. Set aside.
Put the cardamom, coriander, fenugreek, allspice, cloves and cinnamon in a small skillet and toast over medium-low heat, shaking the pan regularly, until fragrant, about 4 minutes. Cool slightly.
Grind the toasted spices in a spice grinder to a fine powder. Add to the chile powder mixture and whisk to combine. Sift the spice mixture onto a piece of parchment paper, return to the bowl and whisk again. Return the pieces left in the sifter to the spice grinder and grind again as finely as possible; whisk into the spice mixture. Set aside.
To finish the niter kibbeh: Line a strainer with dampened cheesecloth. Skim the foam from the top of the butter and discard. Ladle the butter through the strainer, leaving behind the milk solids on the bottom of the pan.
For the chicken stew: Put the chicken in a nonreactive bowl and toss with the lemon juice and 1 teaspoon salt. Let stand at room temperature for 30 minutes.
While the chicken is marinating, prepare a bowl with ice water. Bring a medium saucepan of water to a boil and salt generously, making sure there is enough water to cover the eggs by 1 inch. Carefully add the eggs, bring back to a gentle boil and cook for 6 minutes. Transfer the eggs to the ice water, and shake or tap gently to crack the shells. Remove the eggs from the water and, when cool to the touch, peel. Set aside; do not refrigerate or they will not warm up in the sauce.
Put the onions in a large skillet over medium heat. Cook, stirring constantly, until golden, about 10 minutes, taking care not to burn them. You may need to reduce the heat as the onions dry out.
Increase the heat to medium high; add 1/3 cup of the niter kibbeh, 1/4 cup of the berbere, the garlic, ginger, tomato paste and black pepper, and cook, stirring, for 1 minute. Add the chicken, turning to coat well with the butter mixture, and then leave the chicken skin-side down in the pan.
Add the chicken stock, bring to a simmer, cover, reduce the heat to low and cook at a gentle simmer until the chicken is very tender, about 40 minutes. Remove the lid, increase the heat to medium and simmer, stirring occasionally, until the liquid is reduced and the sauce is very thick, about 45 minutes, occasionally spooning the sauce over the chicken.
Remove the pan with the chicken from the heat and add the eggs, turning to coat them in the sauce. Cover the pan and let rest for 5 minutes.
To serve, place the chicken thighs and eggs on injera or serving plates, and spoon the sauce over.
Starting the onions in a dry pan is traditional for this dish and adds a toasty taste. Just be careful not to let the onions burn. This recipe makes more than enough berbere and niter kibbeh to make the chicken. Refrigerate any leftovers to use in other Ethiopian recipes.