In a medium mixer bowl combine flour, sugar, butter, salt, and vanilla. Beat at low speed, scraping bowl often, until well combined and mixture resembles small peas (1-2 minutes). Stir in 1/2 cup pecans. Set aside 3/4 cup of this mixture.
Press remaining crumb mixture into a buttered 9x13 baking pan or glass dish. Spread jam over crumb mixture. Sprinkle with remaining cup of chopped pecans and reserved crumb mixture.
Bake for 35-40 minutes or until crumb mixture is lightly browned and jam is bubbly. Cool completely cut into squares.