Preheat oven to 400 degrees. In a small skillet, melt 1/2 tablespoon of butter. Saute jalapenos until soft, about 2 minutes. Place in a small bowl with Cheddar cheese and coat with 1 tablespoon of flour. In another bowl, combine the rest of the flour with baking powder and salt. Cut in remaining butter with a fork until the butter is pea-size.
Lightly whip eggs and cream and add to the flour-and-butter mixture. Using a wooden spoon, fold mixture until it begins to come together. Add the Cheddar-and-jalapeno mixture to the dough and mix until everything is incorporated. Refrain from over mixing.
Turn out the dough onto a well-floured surface and knead gently for less than one minute. Roll dough 3/4 to 1-inch thick and cut into 8 triangles. Brush with egg wash and place on well-oiled baking sheet.