In a small mixing bowl, combine the yeast, 1 teaspoon sugar, and 1/4 cup of the warm water. Stir to dissolve and set aside. In an electric mixer, beat the eggs and remaining 3/4 cup sugar until thick and pale yellow in color. Change the mixer attachment to a dough hook. With the machine running slowly add the yeast mixture, melted butter, salt, milk, and half-and-half. Add the flour, 1 cup at a time. Mix until the mixture forms a soft ball, leaves the sides of the bowl, and climbs up the dough hook. Remove the dough and turn into a lightly oiled bowl. Cover the bowl with plastic wrap and set the bowl in a warm, draft free space. Let the dough rise until double in size, about 1 1/2 hours. Turn the dough out onto a floured surface and dust the surface of the dough with flour. With a rolling pin, roll out the dough, about 1/4-inch thick, in the shape of a rectangle. Using a 3-inch round cutter, cut the dough into circles. Place the rounds on a baking sheet. Cover the dough with a greased piece of plastic wrap (this will prevent the dough from sticking to the wrap) and let the dough rise until double in size, about 30 minutes. Preheat the fryer to 350 degrees. Gently fry a couple of the circles at a time, until golden brown, about 3 to 4 minutes, flipping occasionally for overall browning. Remove the doughnuts from the oil and drain on a paper towel-lined plate. Fit each pastry bag with small round tips. Fill each bag with a different filling. Pipe the doughnuts, alternately with the different fillings. Sprinkle some of the filled doughnuts with powdered sugar. Glaze the remaining donuts with the 2 different glazes. Serve on a large serving platter.

In a mixing bowl, combine the egg yolks, cornstarch, and 1 cup of the heavy cream. Whisk to blend well. Set aside. Combine the remaining 1 1/2 cups cream, sugar and vanilla extract in a large heavy-bottomed saucepan over medium heat. Whisk to dissolve the sugar and bring to a gentle boil, about 10 minutes. Slowly add the egg yolk mixture, whisking constantly and cook until it thickens, about 5 minutes. Be forewarned: the mixture will break. Don't be alarmed. Pour it into a glass bowl. Press a piece of plastic wrap down over the surface of the mixture to prevent a skin from forming. Let cool completely at room temperature. When cooled pour the mixture into the bowl of an electric mixer fitted with a wire whip. Beat at a medium speed to combine the mixture. If it will not combine, warm another 1/2 cup heavy cream and slowly add it to the mixture. Whip until you have a thick and creamy custard.

RASPBERRY FILLING: 4 cups raspberries 1 cup water 1/2 cup sugar 2 tablespoons cornstarch

In a saucepan, combine raspberries, 3/4 cup of water and sugar. Bring to boil. Simmer for 15 to 20 minutes or until raspberries have broken down. Remove mixture from the heat and strain out the seeds. Return the strained mixture to the heat. Dissolve the cornstarch in the remaining 1/4 cup of water. Whisk the slurry into the raspberry mixture. Bring the mixture back to a boil. Simmer for 5 more minutes. Remove from heat and cool completely.