Heat oil in a pan over medium heat. Add shallots and garlic, cooking until translucent. Add mushrooms, salt, and pepper, cooking until mushrooms are golden brown. Remove from heat.
2. Step
In a medium bowl, combine mushrooms, cream cheese, egg yolks, and chives, stirring until evenly incorporated. Set aside.
3. Step
Preheat oven to 400°F (200°C).
4. Step
On a cutting board, season both sides of the steak with salt and pepper.
5. Step
Cut about ¾ of the way through the steak, making the incisions 1-inch (2 cm) part.
6. Step
Pack a spoonful of the mushrooms mixture into each cut in the steak.
7. Step
Heat the oil in a pan over high heat. Sear the steak for about 30 seconds, then bake for 10-15 minutes, depending on how you like your steak cooked. Slice and serve.
